EPA-AA-SDSB-84-5

                   Technical Report
           Characterization of the Rolling
         Resistance of Aftermarket Passenger
                      Car Tires
                          By

                     Nancy Egeler


                      July  1984
                        NOTICE

Technical Reports  do not  necessarily represent  final  EPA
decisions  or  positions.   They  are  intended  to  present
technical  analysis   of   issues   using  data   which   are
currently available.  The  purpose in the  release  of  such
reports  is   to   facilitate  the  exchange   of  technical
information  and   to  inform  the   public   of   technical
developments   which may  form the  basis  for  a final  EPA
decision, position or regulatory action.
       Standards Development and Support Branch
         Emission Control Technology Division
               Office of Mobile Sources
             Office  of Air  and Radiation
        U. S. Environmental Protection Agency

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I.    Background

     In the  early 1980s, EPA  began to  investigate  the effects
of  tire  rolling  resistance.   The  benefits  of  improved  (i.e.,
lower)  rolling   resistance  include:   reduced   vehicle  fuel
consumption,  lowered  exhaust   emissions and  possibly  reduced
discrepanies between EPA and on-road vehicle fuel economy.

     The  amount   of  fuel  consumed by  a vehicle is  a  direct
function  of  the  tires that are  used.[l]   Improvements  in the
rolling  resistance  of  tires  would  significantly  reduce  the
amount of fuel consumed daily in the United States.

     Vehicle   exhaust   emissions   also   depend   upon   rolling
resistance.    A   strong  correlation  exists   between   rolling
resistance   and   oxides  of   nitrogen  (NOx)   emissions;   NOx
emissions increase with  the use of tires having  higher rolling
resistance.   Carbon  monoxide  (CO)  emissions are  also  affected
by  tire   rolling  resistance;   CO  emissions   increase  with
increases   in  tire   rolling   resistance.    In   the   case  of
hydrocarbons   (HC),  a  weak   relationship   exists  between  HC
emissions and  rolling resistance.[2]

     Variations  in tire  rolling  resistance  may  contribute  to
the differences  between EPA-measured fuel  economies and those
observed  by  consumers.   Part  of  this  discrepancy may  result
from  aftermarket  tires  having significantly different rolling
resistance  from  the tires  on  the  corresponding  production and
EPA certification vehicles.

II.   Summary

     The  purpose  of this  program  was  to  compare the  rolling
resistance  of tire  model  lines  within a  sales-representative
test  matrix   and  to   determine   which tire   characteristics
influence rolling resistance.

     The  tires for  this test program  included  all tires,  as
defined by manufacturer/brand  name (i.e.,  Goodyear,  Sears) and
model (i.e.,  Arriva,  Guardsman),  that accounted  for  at least 1
percent  of  1981  replacement  market  sales.   Additional  tires
were  selected to   increase   the  representation  of  as  many
manufacturer/brand names as possible  and to maximize the total
fraction  of  the  replacement  market  represented.    The  test
matrix  used   consisted  of   252   tires,   from   20   different
manufacturer/brand  names and  54  different  model lines.   This
matrix covered approximately 54 percent  of  the  1981  replacement
market.

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                              -2-
     Signifleant  correlations  were  found   between  a  tire's
rolling resistance  and the tire  model,  construction  type,  and
body cord.   An inconclusive relationship was  found between belt
fiber and rolling resistance.

     Comparisons were  made between  different tires based upon
the  mean  rolling resistance  coefficient  (RRC)   of the  model.
Table 1 lists the models  tested and their construction type, in
order of increasing  mean RRC.   The three models with the lowest
rolling resistance were:

     1.     BF Goodrich Lifesaver XLM
     2.     Uniroyal  Steeler
     3.     Delta Radial II

     In the  analysis  of  construction type,  it   was  determined
that average  radial-ply  tires have  20.2  percent  lower  rolling
resistance than  bias-belted tires  and  26.0 percent lower than
bias-ply.

     The analysis of  body  cord  showed,  with a  high  level  of
statistical  confidence  (p =   0.01),  that  among  steel-belted
radial tires those having  polyester  body  cords had 8.8 percent
lower  mean  rolling  resistance  than  those  having rayon  body
cords.

     The sample  sizes  available for  analysis of the  effect of
belt fiber  on rolling resistance were  not,   for all   types  of
belt fiber,  large enough to  state  definitely that the use  of
one  type  lowers  tire rolling  resistance.   It  was found that
radial tires with steel + fiberglass belt  fibers  tended to have
lower rolling resistance than those  with  fiberglass belt fibers
and those with  steel  belt fibers;  aramid  belt fiber  tended to
have higher rolling  resistance than the other  types.

     Little  relationship  was  observed between  a  tire's  price
and  its rolling  resistance.   That  is,  the price of a  tire  is
not a good indication of its rolling resistance.

     It  was  determined  that   rolling  resistance  results  are
consistent  regardless  of  the  date  of  manufacture   (within  a
reasonable amount of time) or test  date.   However, it  should be
noted that:  1)  all  tires  used  in this  program  were  purchased
within  a  small  amount of time,  2) all  members of each  model
were purchased from the same  supplier,  and 3) only four or  six
tires  of   each   model  were  tested.   The   above  should  be
considered when interpreting the results of this  analysis.

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                              -6-
     Finally, two  tires were  tested repeatedly  throughout the
program to  check for any variations in the  test results  as  a
function  of time.   Only minute  changes  in  the test  results
caused by time-dependent factors were observed,  reflecting good
test precision and repeatability.

III. Test Program Design

     The test matrix emphasized market  coverage and represented
as  many tire  models as  feasible.   To ensure that  the  test-
matrix was  representative  of tire sales,  detailed knowledge of
the breakdown of the 1981  replacement  tire market  was  needed.
Because of  the  fragmentation and  size  of  the  replacement tire
market, Smithers Scientific Services, Inc.   (SSS)  of  Akron, Ohio
was contracted  to  develop the test  matrix.  SSS  is a testing,
research  and consulting corporation with   extensive experience
in research and testing  of automotive tires.

     EPA  requested  that SSS  supply market  data  and  suggest  a
test matrix.  The matrix which SSS prepared was  based on market
survey data  where  available,  on requests  for data sent  to tire
manufacturers, and,  in a few cases where data were not publicly
available and were  not  released by  tire manufacturers,  through
estimates by Smithers staff.

     The  SSS  matrix   included  every   tire  model   known  or
estimated to represent  1 percent  or  more of the total 1981 tire
replacement  market.   If a  brand  name  represented more  than  1
percent of  the  total market,  but no  individual  model  of that
brand  represented  more than  1  percent,   then  the  two  most
popular models  sold under  that brand name were  included in the
matrix.   The tires included  in  the  SSS  matrix  represented
approximately 56 percent  of the total  1981 replacement  market;
58 models were included.

     This program  had  maximum  resources  of  approximately 300
tests.  Therefore,  some method was  necessary  to distribute the
test   capability over   the  SSS  matrix.    A   previous  test
program[3]  had  indicated good  homogeneity among tires  of one
model,  therefore,   to   emphasize  market  coverage,  tires  were
selected from all of the models of the SSS  matrix.

     For  each of  19 models  having 1  percent  or more  of the
market,  six test  tires were  selected.   For  each of  the  39
models  having less  than  1 percent  of the  market,  four test
tires  were  included.    Because  of  the  small  sample  sizes,
statistical  confidence  in  the results was  somewhat lower  in
this  region of  the  test   matrix.   However,  this  was  judged
acceptable since these  tires represent  a smaller segment of the
market.  The sample sizes of  four  and six provided sufficient

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                               -7-
replicate  testing  to have  good  statistical  confidence  in  the
results from these tires.   Statistical  confidence in the sample
sizes is discussed further in the section entitled "Results."

     The  tires chosen  to  represent each model  were  all  of
14-inch  nominal diameter.   Tires marketed  under the  P-metric
sizing were all P195/75R14,  while alphanumerically  sized tires
were  all  E78-14 or  ER78-14.   These were projected to  be  the
best selling sizes in the passenger  car  tire  replacement market
for 1982.[4]

     The radial tires  in the matrix represent  about 70 percent
of  1981  radial replacement  sales,  while  non-radials  represent
only  37  percent  of  1981  non-radial  replacement   sales.   The
lower  number  of  non-radials   tested   was   deemed   acceptable
because  the  percentage  of  radials sold in  the  replacement
market was increasing when the matrix was  designed and  is still
increasing.

     The test  matrix used in this program is shown  in  Table 2.
Initially, 270 tires were to be  tested,  however,  four models of
the  SSS matrix  became  unavailable  during  the  course  of  the
program.   Therefore, the actual  test matrix  used contained 54
models  rather  than  58,  and  represented  252 tire  tests, instead
of 270.

     As  a  means of  checking  for any  variations in  the  test
results as  a  function of  time,  two tires were chosen  from the
matrix to  serve as  "correlation" tires.   These tires  (Michelin
XWW, P195/75R14) were the single best selling model  included in
the matrix,  and alone represent  6  percent of  1981  replacement
market  sales.   Each  time that  another  group of  tires  (usually
30 to 40)  was  tested,  these  two Michelin tires  were  retested,
and  the results  were  compared  to  those obtained  in  earlier
tests.   These  results,  discussed   in   the   section  "Quality
Control,"  characterize   possible changes  in the test  results
caused  by  calibration  drift,  lack   of  machine  alignment
maintenance, or other unknown time-dependent  factors.

IV.  Test Contractor

     The  actual  testing  of  the tires  in  this  program  was
conducted  by   Standards  Testing  Laboratories,  Inc.,  (STL)  of
Massillon,  Ohio.    STL   has  had  extensive experience   in  tire
testing, including rolling  resistance testing.   STL has tested
tires for  the  Department  of  Transportation's  (DOT) Uniform Tire
Quality  Grading  program,   has  conducted  testing  for  tire
industry  firms, and  has  participated  in round-robin  rolling

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                             Table 1
    Brand & Model
                    Mean Rolling Resistance
                  Coefficients  (RRC) by Models
Construction
BF Goodrich Lifesaver
   XLM
Uniroyal Steeler
Delta Radial II
Laramie Glass Rider
Atlas Silveraire
Firestone Deluxe
   Champion Radial
Michelin XWW
Multi-Mile XL
M. Ward Runabout
General Steel Radial
Uniroyal Tigerpaw
Penney Mileagemaker Plus
Goodyear Arriva
Kelly-Springfield
   Navigator
General Dual Steel III
Multi-Mile Supreme
Goodyear Custom Poly-
   Steel
K-Mart KM-225
Dayton Quadra
Delta Durasteel
   Radial
  RRC
0.00979
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
0.00997
0.01009
0.01018
0.01035
0.01041
0.01048
0.01052
0.01055
0.01059
0.01067
0.01078
0.01087
0.01087
0.01091
0.01097
0.01101
0.01104
0.01109
0.01110

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                        Table  1  (cont'd.)
                    Mean Rolling Resistance
Coefficients
Brand & Model
Firestone 721
Dayton Blue Ribbon
Penney Mileagemaker XP
Firestone Trax 12
Sears Road Handler 78
Summit Steel
Dunlop Goldseal
M. Ward Grappler
Sears Weather Handler
Goodyear Tiempo
Cooper Lifeliner (glass
belt)
Armstrong SXA
Dunlop Generation IV
Cooper Lifeliner (steel
belt)
Michel in XVS
Goodyear Cushion Belt
Polyglas
Armstrong Coronet All-
Season
Kelly-Springfield
(RRC) by Models
Construction
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Bias-Belt
Radial
Bias-Ply

RRC
0.01122
0.01149
0.01152
0.01167
0.01177
0.01176
0.01186
0.01208
0.01212
0.01227
0.01228
0,01232
0.01249
0.01261
0.01363
0.01371
0.01381
0.01393
   Roadmark
Sears SuperGuard
Bias-Belt
0.01409

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                          Table 2

                      Tire Test Matrix

                                                   Number of
	Tire DescriptionE1,2]	       Tires Sampled

 Michelin XWW Radial[3]                                 6
 Firestone 721 Radial                                   6
 Goodyear Custom Polysteel Radial                       6
 Goodyear Power Streak Bias                             6
 Sears Road Handler  78 Radial                          6
 Sears Weather Handler Radial                          6
 Goodyear Tiempo Radial                                 6
 Goodyear Arriva Radial                                 6
 BF Goodrich Lifesaver XLM Radial                       6
 Michelin XVS Radial                                    6
 Sears Guardsman Bias                                   6
 Goodyear Cushion Belt Polyglas Bias-Belted            6
 BF Goodrich CLM Bias-Belted                           6
 Firestone Deluxe Champion Radial                       6
 General  Dual Steel  III  Radial                          6
 Uniroyal Steeler Radial                               6
 General  Steel Radial                                   6
 Sears Super Guard Bias-Belted                          6
 Dunlop Generation IV  Radial                           4
 Firestone Trax 12 Radial                               4
 Firestone Deluxe Champion Bias                        4
 K-Mart KM78 Bias                       .               4
 Multi-Mile Supreme Radial                             4
 Uniroyal Tiger Paw Radial                             4
 Cooper Trendsetter Bias                               4
 Multi-Mile XL Radial                                   4
 Kelly-Springfield Navigator Radial                     4
 K-Mart Economizer Bias                                 4
 Atlas Cushionaire Bias                                 4
 Kelly-Springfield Benchmark Bias                       4
 Armstrong Coronet All-Season Radial                    4
 Dayton Blue Ribbon Radial                             4
 Dayton Quadra Radial                                   4
 Dayton Deluxe 78 Bias                                 4
 Multi-Mile Poly IV Bias                               4
 Atlas Silveraire Radial                               4
 Kelly-Springfield Roadmark  Bias                       4
 Armstrong SXA Radial                                   4
 Cooper Lifeliner Radial (steel belted)                 4
 Dunlop Gold Seal Radial                               4
 Laramie  Easy Rider Bias                               4
 K-Mart KM-225 Radial                                   4
 Uniroyal Fastrak Poly Bias                             4

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                       Table 2 (cont'd.)

                        Tire Test Matrix

                                                     Number of
  	Tire Description[l,23	       Tires Sampled

   Montgomery Ward Runabout All  Season Radial            4
   Cooper Lifeliner Radial  (glass belted)                 4
   JC Penny Mileagemaker XP Radial                       4
   JC Penny Mileagemaker Plus  Radial                     4
   Delta Radial II                                       4
   Laramie Glass Rider  Radials                           4
   Summit Supreme 120 Bias                                4
   Delta Durasteel Radial                                4
   Montgomery Ward Grappler All  Season Radial            4
   Montgomery Ward Road Guard Bias-Belted                 4
   Summit Steel Radial                                    4

   Total:    252   individual   tests,   not   including   repeat
   correlation tests.
[1]   The four  models  which became unavailable are:
           BF  Goodrich Lifesaver LXII  Radial (4)
           General  Ameri-Sprint Bias Ply (4)
           General  Ameri-Sprint Bias Belted (4)
           Uniroyal Fastrak Bias-Belted (4)
[2]   All  radial  tires  are  P195/75R14,   all bias-belted  and
     bias-ply  tires are E78-14 or ER78-14.
[3]   Two of this  sample are correlation tires and were  retested
     periodically throughout the test  program.

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                              -10-
resistance test programs  conducted by the Society of Automotive
Engineers.   Excellent correlations  between  tire test  results
obtained  at  STL,  at  the  General Motors  Proving  Ground,  and at
the   University  of   Michigan   test   laboratory   have   been
demonstrated.[5]    These   correlations   verify   that  observed
variations  in  rolling  resistance  reflect differences  in  the
test tires, not in the test labs or other undetermined factors.

V.   Test Procedure

     The  test  procedure  used  was  the  spindle-force  method
described in "EPA Recommended Practice  for the Determination of
the  Rolling  Resistance  Coefficients,"  which is  attached  as
Appendix A.  The procedure is outlined below.

     A.    Test Equipment

     The  tires  were  tested using a  67.23-inch  diameter  tire
dynamometer.  This machine  is  equipped with a movable carriage,
on  which  the  tire/wheel  assembly is  mounted.   This  assembly
applies  the  specified  test  load perpendicular to  the  test
wheel.  The  tire  and  test wheel are then driven  at  the  desired
speed.

     B.    Break-In

     A break-in procedure was  required,  since automobile tires
undergo  a slight,  permanent  growth   (increased  circumference)
when  first  run under operating conditions.   The  break-ins were
performed by installing the tires  on the test machine under the
standard test conditions  (load, inflation pressure,  and ambient
temperature), and  running the  tire at  50  miles  per hour  (the
standard test speed) for a minimum of one hour.

     C.    Test Conditions

     Standard  conditions  for  this  test  include  an  ambient
temperature  between  70F  and   80F,  and  specific  loads  and
inflation pressures.  The cold  inflation pressure is 32 psi for
alphanumercially  sized  tires  and 35  psi  for P-metric  sizes.
The  test   load  is  defined  as  80  percent of  the  Tire  &  Rim
Association (T&RA) design load  for the given  tire,  at the given
cold  inflation  pressure.   Since  all  tires were  the  same size,
the test  load on  the  tire was  the same  in all cases; the T&RA
design load  is  1400  pounds  force (lbf),[6]  thus the test load
is 1120 Ibf.  Use  of  the same  test load (within  5-  Ibf)  on all
of the tires permits  direct comparisons  to be made  between the
measured rolling resistances of different tires.

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                              -11-
     D.    Thermal Conditioning

     After the  tire  break-in is completed, the  tire  is left in
the thermal environment of  the test equipment for a  minimum of
three hours.  At  the end of this time,  the  inflation pressure
is  checked and  readjusted  to the  prescribed  cold  inflation
pressure, if necessary.

     E.    Tire Warm-Up

     The  tire/wheel  assembly  is  then  reinstalled  on  the  test
machine (if it was removed  before  thermal conditioning),  loaded
against  the  test surface  at the  specified test load, and run
for at least  45 minutes.  This allows the tire  temperature and
operating inflation pressure to reach equilibrium.

     F.    Test Measurements

     When   the    warm-up   is    completed   and    with   the
tire/dynamometer system operating  at  the  test speed of 50  mph,
the following are measured and recorded:   tire spindle force
(which will be  converted to rolling  resistance force),  normal
load on  the  tire, ambient  temperature, loaded tire  radius, and
final inflation pressure.

     G.    Parasitic Losses

     A small  amount of energy  is  absorbed parasitically  by the
test machine  through  bearing friction which  may be  inherent in
the measurement.  The parasitic losses  must be  subtracted  from
the spindle force to isolate the tire's rolling resistance.

     To  determine  parasitic test  machine  losses,  the load on
the tire  is  reduced  to  a  value  just sufficient  to  maintain
rotation at 50 mph without  slippage (approximately 10 Ibf); the
spindle  force is  then measured.   This  value  represents  the
parasitic  test   machine   loss  and  is   subtracted   from   the
previously measured  spindle  force to  yield the  net  spindle
force.

     H.     Averaging Technique

     An averaging technique was used to  eliminate  any possible
effects  of minute  machine or  tire  misalignments.    In  this
technique, developed by engineers  at  the  General Motors Proving
Grounds,   the  tire/dynamometer  assembly  is run  both  clockwise
and  counterclockwise.   Spindle  force  readings  are  taken  for
each rotation direction and the parasitic  losses are  subtracted
from each  value,  as  described above.   The  two values  of  net
spindle  force are then  averaged  to  obtain  the final spindle

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                              -12-


force value.  This averaging  removes  any systematic directional
bias  which might  exist  in the  machine or  measurement system.
This  is  a slight  deviation  from  the EPA Recommended  Practice
given  in  Appendix A,  however, it  is  a  desirable refinement for
machines using the spindle-force method.

VI.   Data Reduction

     After averaging the net spindle  forces  to  obtain the final
spindle force,  the final spindle  force must be  converted to a
rolling resistance (or  energy  dissipation)   force.   This  is  a
necessary  force   conversion,  and  is   not   a  correction  for
equivalent flat-surface  rolling  resistance.   The  conversion is
given by the equation:[7]

     Fd = Fx (1 + r/R)                                        (1)

where:

     Fx = final spindle force

     r = loaded tire radius

     R = test surface radius (33.615 in.)

     Fd = rolling resistance force.

     Since  all  of  the  tires tested  in this  program were of
similar sizes and  load ranges,  and were loaded to  1120+5 Ibf,
comparisons between different tires may be  made on the basis of
rolling resistance force.   However,  more   general  comparisons
between tires  having different  load  ranges, aspect  ratios, or
nominal diameters  must  be made  on the  basis  of  their  rolling
resistance  coefficients  (RRC).    The  dimensionless  RRCs  are
obtained  by  dividing the  rolling resistance  force  Fd  by  the
normal load on the tire during the test, L:

     RRC = Fd/L                                              (2)

     Computation of  the tire  RRCs was  the  extent of  the data
reduction  conducted by  STL.   A  sample  STL   data  sheet,  showing
all  of the information discussed so far, is  included as Table 3.

     The  rolling  resistance  of  an  automobile   tire  is  also
dependent   on   the   ambient  temperature.    The  effect   of
temperature  on  rolling  resistance .  is  small  as  long as  the
ambient temperatures remain  within a  relatively  narrow  range:
70-80F.   All  tests  in this program  were conducted within this
temperature  range, and  the  rolling  resistance  corrected  to
standard  temperature  (75F)   using  the  following  correction
formula:

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                                                Table  3
                             POWER IDSS/RCLLINTi RESISTANCE TEST
OISTCMER
EPA
TEST TECHJICIAN  D. Langman
                   TIRE SIZE
P195/75R14
                                  TESTING
                                 LABORATORIESINC.
            P:O. IOX SM  IMS HARSH AVf., S.f.  MASSIUON, OHIO 44Mfc
            Mutitton Telephone:      (216) 813-6541
            Owed Akron Telephone:    (214) 251-1901
STL JOB NO. J 1-285 TIRE BRAND Goodyear TEST RIM SIZE & ONTOUR 14x5.50
TEST NO.EPAR 347 (4243) TIRE SERIAL NO.
CHECKED BY D. L. Fuller TIRE NAME
IRE LOAD
bs. (Pz) !
1122









80-147
TEST
PRESSURE
PSI.
39.3
V









TIRE ROLL.
RADIUS
In. ^r)
11.76










TEST 1
SPEED 1
mph
50.0










AMBIENT
TEMP.
F
76










MDKATK0422 BVTE
June 22,
1983
Tiemod TIRE CONSTRUCTION
NET SPINDLE
FORCE
CCU (Fl)
+9.8





'




NET SPINDLI
FORCE
CW (F2)
-10.5


.-







F! + ^2
2
-.35










ROLLING
RESISTANCE
Ibs. (FR)
13.70.








1

REGRESSION
VALUE








 '


ROLLING
RES. COEF.
ibs. (FR:
.0122

I-1
u>
1








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     Fd* = Fd [1 + ct (tx - t,)],                            (3)

where:

     Fd* = temperature-corrected rolling resistance force

     Fd  = uncorrected rolling resistance force

     t,  = the standard test temperature (75F)

     tx  = the measured test ambient temperature

     ct  = the temperature correction coefficient
     (3.3xlO"VF) .

     The   relationship    between    rolling    resistance    and
temperature  within  the  specified  temperature  range  is  linear.
However,  the  function  may  vary   among   tires  of  different
construction or made with  different materials.  Therefore, when
using the temperature correction formula,  one  must  develop the
temperature  correction   coefficient  based  on  knowledge of the
tire   types   and  materials   being   used.     The   temperature
correction  coefficient   (ct)  represents  the  amount of  change
in rolling resistance corresponding to a change  in temperature
of  one  degree  Fahrenheit.   For   this  test   program,  it  was
determined that 3.3  x 10"s  was the  optimal value for ct.[6]

     Explanations of the details of  data  reduction methods used
with rolling resistance data can be found in reference [7].

VII.  Statistical Analysis

     The data  from  the  rolling resistance tests of  252  tires
were analyzed  to  learn which   characteristics  affect  rolling
resistance using  an  analysis of variance.   This analysis  tests
the  hypothesis  that  N  given  population   means  are  the  same
(i.e.,   the   null  hypothesis) against  the  alternate  hypothesis
that,  for  at  least  two  of  the tires  tested,  the means  are
unequal.  Rejection  of  the  null  hypothesis  is evidence that
variation  in   rolling  resistance  is  based  on  the   tire
characteristic.    The   significance   of   rejecting  the   null
hypothesis  is  stated  in  terms of the  probability  of  being
incorrect  by   doing  so.    This   probability  leads   to  the
percentage level of  confidence  that one  can state that a tire
characteristic  has  an  effect  on  rolling  resistance.    The
confidence  levels  given  in  the following  discussion  signify
that the mean rolling resistance of a subset of tires sharing a
characteristic (e.g., a  subset  of  radials)  does not  equal the
mean rolling resistance  of the  entire group  of  tires.   Hence,
the  tire  characteristic  affects   rolling  resistance   and  a
relationship exists.

-------
                              -15-
     An  analysis  of  variance,   as  described  in  the  previous
paragraph,   was   performed   for   each   of   the   following
characteristics:

     1.     Model
     2.     Construction type
     3.     Body cord
     4.     Belt fiber

To  investigate  the  consistency  of  tire  manufacture  as  it.
affects  rolling  resistance,  the means   from  the  same  models
which  had  been  manufactured  at  least one  week  apart  were
compared.  To determine whether  the price of a tire  is  related
to its rolling resistance,  a  linear regression between purchase
price  and  rolling  resistance  was  performed.    Finally,  the
standard deviations for all model lines  tested were examined to
determine the reliability of the test results.

VIII.  Results

     The results for all 252 tires  tested are  shown in Appendix
B.   Table  4 provides  an overview  of all  tire  characteristics
examined  and  their effects  on  rolling. resistance; Tables  5-9
show the results of each of  the analyses  performed.

     A.     Model

     Through an analysis  of variance  of the 252 tires  from 20
different   companies   constituting   the   final   matrix,   a
relationship between model  and  rolling resistance was observed,
with 99 percent confidence.

     Mean RRC was calculated  for each model.  The  three models
with the lowest rolling resistance were:

     1.     BF Goodrich Lifesaver XLM
     2.     Uniroyal Steeler
     3.     Delta Radial II

The three models with the highest rolling resistance were:

     1.     Atlas Cushionaire
     2.     Multi-Mile Poly IV
     3.     Uniroyal Fastrak  Poly

Table  5  lists,  in  increasing  order,  the rolling  resistance
force and mean RRC for each model tested, and  other statistical
results of this analysis.

-------
                              Table 4
                       Summary of Effects  of
            Tire Characteristics On Rolling Resistance
     Tire
Characteristics

Model
  Sample Used
170 radial
from 20
companies
tires
                   60 bias-ply
                   tires from
                   12 companies
                   22 bias-belted
                   tires from 4
                   companies
Construction
All tires
tested.
Result Observed

Identity of
model affects RRC.
                            Models with
                            lowest RRC:

                            BF Goodrich
                              Lifesaver XLM
                            Uniroyal Steeler
                            Delta Radial II

                            Identity of
                            model affects RRC,
                            Models with
                            lowest RRC:

                            Goodyear Power
                              Streak
                            Laramie Easy Rider
                            Firestone Deluxe
                              Champion

                            Identity of
                            model affects RRC.
                 Models with
                 lowest RRC:

                 Goodyear Cushion
                   Belt Polyglas
                 Sears Super Guard

                 Radial plies had
                 20.3% lower mean
                 RRC than bias-
                 belted tires and
                 26.1% lower mean
                 RRC than bias-ply
                 tires.

-------
                         Table 4 (cont'd)
                       Summary of Effects of
            Tire Characteristics On Rolling Resistance
     Tire
Characteristics

Body Cord
Belt Fiber
  Sample Used

Steel-belted
radials only
Radial-ply
only
Price
Rolling
Resistance
Consistency
Over Time
All construction
types
4 groups of two
models of steel-
belted radials
made in different
weeks
Result Observed

Polyester body
cord had 8.8%
lower mean RRC
than rayon body
cord.

Steel + fiberglass
-belted had
0.081% lower mean
RRC than fiber-
glass-belted
tires,
1.27% lower mean
RRC than steel
-belted tires,
and 13.93%
lower mean RRC
than aramid-
belted tires.

Rolling resistance
is not linearly
dependent on price

RRC remains
constant with
date of manu-
facture.

-------
                                              Table 5

                                Rolling Resistance Data - Means by
                                         Brand and Model
Rolling Resistance
Force (Ibf)
Brand and Model
BF Goodrich Lifesaver
XLM
Uni royal Steeler
Delta Radial II
Laramie Glass Rider
Atlas Silveraire
Firestone Deluxe
Champion Radial
Michelin XWW
Multi-Mile XL
M. Ward Runabout
General Steel Radial
Uni royal Tigerpaw
Penney Mileagemaker Plus
Goodyear Arriva
Kelly-Spr ingf ield
N Const. [1]
6
6
4
4
4
6
6
4
4
6
4
4
6
4
R
R
R
R
R
R
R
R
R
R
R
R
R
R
x~[2]
10.
11.
11.
11.
11.
11.
11.
11.
11.
11.
11.
12.
12.
12.
96
15
30
41
61
67
75
79
84
85
93
08
16
18
s [3]
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
20014
46529
23200
12100
06300
25300
10700
24400
15800
40450
30522
15100
23811
02563
RRC
x~
0.00979
0.00997
0.01009
0.01018
0.01035
0.01041
0.01048
0.01052
0.01055
0.01059
0.01067
0.01078
0.01087
0.01087
90% Confidence
s Interval around RRC [4]
0.00018
0.00042
0.00020
0.00011
0.00007
0.00023
0.00010
0.00021
0.00014
0.00035
0.00026
0.00014
0.00022
0.00023
0
0
0
0
0
0
0
0
0
0
0
0
0
0
.00964-0
.00963-0
.00985-0
.01005-0
.01270-0
.01023-0
.01040-0
.01028-0
.01033-0
.01029 0
.01036-0
.01061-0
.01069-0
.01060-0
.00994
.01031
.01032
.01031
.010430
.01060
.01056
.01077
.01067
.01088
.01098
.01095
.01105
.01114
Navigator

-------
         Table 5 (cont'd.)

Rolling Resistance Data - Means by
         Brand and Model
Rolling Resistance
Force (Ibf)
Brand and Model
General Dual Steel III
Multi-Mile Supreme
Goodyear Custom Poly-
Steel
K-Mart KM-225
Dayton Quadra
Delta Durasteel
Firestone 721
Dayton Blue Ribbon
Penney Mileagemaker XP
Firestone Trax 12
Summit Steel
Sears Road Handler 78
Dunlop Goldseal
M. Ward Grappler
Sears Weather Handler
N Const. [1] X
6
4
6
4
4
4
6
4
4
4
4
6
4
4
6
R
R
BB
R
R
R
R
R
R
R
R
R
R
R
R
12.
12.
12.
- 12.
12.
12.
12.
12.
12.
12.
13.
13.
13.
13.
13.
[2]
22
28
34
37
41
46
58
87
92
52
17
18
28
54
60

0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
s [3]
28700
16800
16967
21700
22400
13800
21500
14400
23300
08810
35400
08900
15300
93100
26900
RRC
X
0.01091
0.01097
0.01101
0.01104
0.01109
0.01110
0.01122
0.01149
0.01152
0.01167
0.01176
0.01177
0.01186
0.01208
0.01212
s
0.00025
0.00014
0.00016
0.00020
0.00019
0.00013
0.00017
0.00013
0.00021
0.00009
0.00032
0.00008
0.00015
0.00083
0.00025
90% Confidence
Interval around RRC [4]
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
01071-0.
01080-0.
01088 0.
01081-0.
01086-0.
01095-0.
01108-0.
01134-0.
01123-0.
01107-0.
01139-0.
01170-0.
01169-0.
01110-0.
01192-0.
01112
01113
01113
01127
01131
01126
01136
01165
01172
01127
01214
01183
012044
01306
01233

-------
                                            Table 5 (cont'd.)

                                   Rolling Resistance Data  - Means  by
                                            Brand and Model
Rolling Resistance
Force (Ibf)
Brand and Model
Goodyear Tiempo
Cooper Lifeliner (glass
belt)
Armstrong SXA
Dunlop Generation IV
Cooper Lifeliner (steel
belt)
Michelin XVS
Goodyear Cushion Belt
Polyglas
Armstrong Coronet All-
Season
Kelly-Springfield
Roadmark
Sears SuperGuard
Goodyear Power Streak
Laramie Easy Rider
Firestone Deluxe
N Const. [1]
6
4
4
4
4
6
6
4
4
6
6
4
4
R
R
R
R
R
R
BB
R
BP
BB
BP
BP
BP
X
13.
13.
13.
14.
14.
14.
15.
15.
15.
15.
15.
16.
16.
[2]
74
76
80
00
13
59
35
48
62
80
80
00
04
s [3]
0.33482
0.04900
0.06700
0.35800
0.19500
0.09600
0.16012
0.13700
0.31470
0.25700
0.37244
0.52600
0.29000
RRC
X
0.01227
0.01228
0.01232
0.01249
0.01261
0.01363
0.01371
0.01381
0.01393
0.01409
0.01411
0.01428
0.01431

0
0
0
0
0
0
0
0
0
0
0
0
0
s
.00028
.00005
.00005
.00032
.00017
.00011
.00013
.00014
.00027
.00023
.00036
.00047
.00027
90% Confidence
Interval around RRC [4]
0
0
0
0
0
0
0
0
0
0
0
0
0
.01204-0.
.01222-0.
.01227-0.
.01211-0.
.01241-0.
.01354-0.
.01360 0.
.01365-0.
.01361-0.
.01390-0.
.01381-0.
.01372-0.
.01399-0.
01250
01233
01238
01287
01280
01372
01382
01397
01425
01428
01440
01483
01462
   Champion Bias-Ply
Montgomery Ward Road
   Guard
BB
16.08
0.21200   0.01433   0.00018    0.01411-0.01455

-------
                                            Table  5 (cont'd.)

                                   Rolling Resistance Data - Means by
                                            Brand and Model
Rolling Resistance
Force (Ibf)
Brand and Model
BF Goodrich Belted
CIM
Sears Guardsman
Dayton Deluxe 78
Summit Supreme 120
K-Mart Economizer
Kelly-Spr ingf ield
Benchmark
K-Mart KM-78
Cooper Trendsetter
Atlas Cushionaire
Multi-Mile Poly IV
Uni royal Fastrak Poly
Combined
N Const. [1]
6
6
4
4
4
4
4
4
4
4
4
252
BB
BP
BP
BP
BP
BP
BP
BP
BP
BP
BP

X [2]
16.18
16.46
16.55
17.30
17.35
17.21
17.92
18.21
18.40
18.41
18.71
13.96

0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
2.
s [3]
09930
47700
11100
25400
13600
87260
21100
54700
50300
08700
71616
214
RRC
X
0.01445
0.01468
0.01477
0.01546
0.01549
0.01558
0.01599
0.01624
0.01641
0.01644
0.01672
0.01248

0.
0.
. 0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
s
00008
00043
00008
00021
00014
00035
00020
00048
00045
00007
00061
00199
90% Confidence
Interval around RRC [4]
0
0
0
0
0
0
0
0
0
0
0
0
.01438-0
.01433-0
.01467-0
.01521-0
.01533-0
.01517-0
.01575-0
.01568-0
.01587-0
.01635-0
.01600-0
.01227-0
.01452
.01503
.01486
.01570
.01565
.01600
.01623
.01680
.01694
.01653
.01743
.01261
[1]  Construction type:
     R = radial-ply
     BB = bias-belted
    JBP = bias-ply
[2]  x = mean
[3]  s = standard deviation
[4]  90 percent confidence interval means that one has  90  percent "confidence" that the variance of RRC is
    within the given limits.

-------
                              -22-
     B.     Construction Type

     All   rolling   resistance   data   were    stratified   by
construction type and the mean  for  each type calculated.  Table
6 shows the results.

     A  definite  relationship  between  construction  type  and
rolling  resistance  was  observed.   Of  the  three  construction
types  tested  (radial-ply;  bias-belted;  and   bias-ply),   the
rolling  resistance   mean  of radial-ply  (N =  170)  was  20.2
percent lower than bias-belted  (N = 22) and 26.0 percent  lower
than bias-ply  (N =  60).   This  relationship was observed  with
99.9 percent confidence and confirmed previous findings.[3]

     C.     Body Cord

     It was  observed  with 99.9  percent confidence that,  among
steel-belted radials,  a relationship  exists between  body  cord
and rolling resistance.   Tires of two different  body  cords  were
tested:    polyester   and   rayon.   Steel-belted  radials   with
polyester body cord  had lower  mean rolling resistance (RRC  =
0.011121, N  = 100)  than steel-belted  radials with  rayon  body
cord (RRC = 0.012100, N =  12).   Table 7 shows the  mean  RRC for
the two types of body cord.

     Comparisons were made  to test  for the  effect  of  body cord
on rolling resistance only for  steel-belted  radials because all
other types  of  tire were  made  exclusively of polyester  body
cord.

     D.     Belt Fiber

     A relationship was observed, subject  to the caveats  given
below,  between  the  type  of belt material  in radial  tires and
its  rolling  resistance.   Among  radials, tires  made  with  four
different  belt  materials  were tested:    steel,   fiberglass,
aramid  and  steel  +  fiberglass.   Steel   +  fiberglass-belted
radials (N = 4)  had  the  lowest  mean rolling resistance followed
by  fiberglass-belted  (N  =  40),  steel-belted  (N  =   110),  and
lastly,  aramid-belted radials  (N =  4).  Table 8 shows the mean
RRC  and  mean  rolling  resistance  force for  radial  tires  of
different belt types.

     One should  note  the  small  sample size  of the  above groups
in   interpreting   these    results.     Although     steel    +
fiberglass-belted and  aramid-belted  tires  had  the  lowest and
highest mean  rolling  resistance, respectively,  only  one  model
(four  tires)  was  tested   in   each  sample.    Therefore,   the
observation really is only that  the steel +  fiberglass tires of
one manufacturer were of slightly lower rolling resistance than
the steel-belted tires of many  manufacturers.   The same can be
said for  aramid-belted  tires.   Thus, a  larger sample  is needed
before   any   statistically   valid   conclusions   are  reached
regarding   the   relative   rolling   resistance  of   steel   +
fiberglass- and aramid-belted tires.

-------
                                     Sable 6

                 Rolling Resistance Data - Means by Construction
Rolling Resistance
Force (Ibf)
Construction
Radial
Bias-belted
Bias-ply
Combined
N
170
22
60
252
xtl]
12.62
15.83
17.07
13.96
s[2]
1.059
0.377
1.1128
2.214
RRC
3?
0.01128
0.01413
0.01525 .
0.01248
s
0.00099
0.00033
0.00099
0.00199
90% Confidence
Interval around RRC[3]
0.01116-0.01141
0.01401-0.01425
0.01504-0.01547
0.01227-0.01268
     x = mean
C2]  s = standard deviation
[3]  90 percent  confidence interval means  that  one has  90 percent "confidence"
     that the  mean  RRC  of all  tires  of  the specified  category  is  within the
     given limits.

-------
                                   liable 7

                Rolling Resistance Data - Means by Body Cord
                        (Steel-Belted Radials Only)[l]
Force (Ibf)
Body Cord
Polyester
Rayon
Combined
N
100
12
112
X
12.456
13.221
12.538
s
.8996
1.5040
1.0012
RRC
X
0.011121
0.012100
0.011226
s
0.000798
0.001666
0.000968
[1] Only steel-belted radial s were  examined for the effect  of body cord on
    rolling  resistance,   since  all   other   types  of   tires  were  made
    exclusively of polyester body cord.

-------
                                   Table 8

                Polling  Resistance Data - Means  by Belt Fiber
                        (Radial Construction Only)[l]
Rolling Resistance
Force (Ibf)
Belt Fiber
Steel + Fiberglass
Fiberglass
Steel
Aramid
Combined
NC2]
4
40
112
4
160
X
12.437
12.434
12.538
14.151
12.550
s
. 14307
.94363
1.00120
.27535
.99416
RRC
X
0.011085
0.011094
0.011226
0.012629
0.011225
s
0.000134
0.000842
0.000967
0.000243
0.000939
[1] Only radial  tires were  used  in this  analysis  because among  the 22
    bias-belted  tires,  12 were fiberglass-belted,' and  for 10  tires  the
    information  was  not obtained.   Bias-ply  tires  were  not  used  in  the
    analysis since they do not contain belts.
[2] Of 170 radials tested, only 160 were examined  because the information
    was not obtained for 10 tires.

-------
                              -26-
     It  should also  be  noted that  while  steel +  fiberglass
radials  and fiberglass  radials  had the  lowest  mean  rolling
resistance, the three models  with the lowest rolling resistance
were steel belted  (BF Goodrich Lifesaver XLM,  Uniroyal  Steeler
and   Delta  Radial   II).    Furthermore,    although  steel   +
fiberglass-belted  radials  had  the  lowest  mean  RRC,  the  mean
rolling  resistance  force  of   fiberglass-belted  radials  was
slightly lower  than  steel +  fiberglass-belted  radials.   Thus,
the  relationship  between rolling  resistance and belt fiber  is
not as conclusive as the others mentioned above.

     E.    Price

     A  linear   regression  of  purchase   price  (1981  prices)
against rolling  resistance  was performed for  each  of  the three
construction types .to determine whether a  relationship  exists.
It was  observed for all  types that tire price is  not linearly
dependent upon  rolling resistance.   That  is, rolling resistance
cannot be predicted by  the  price of a tire.   Price accounts for
only 10.8 percent of the variation  in radial tires,  2.6  percent
in  bias-ply  tires,  and   8.7  percent  of  the  variation  in
bias-belted  tires.   These   results  agree  with   an  earlier
analysis.[3]   Table  9   lists  all  model  lines,  in  order  of
increasing mean RRC,  and the purchase price of each tire.

     F.    Rolling Resistance Consistency Over Time

     It  was  concluded   from  the  examination that  rolling
resistance  is  consistent  over   time   and  thus  the  rolling
resistance test results reliably  predict the rolling resistance
of any tire from  a particular model.  To determine this, models
were  examined  which were  identical  in every  way  except  that
they were  manufactured  on different dates  (as  indicated by the
DOT  tire  identification).   Table  10  gives  the  details  of this
examination.

     The mean  RRC of  two models,  each  containing two  groups  of
tires  manufactured  during   different   weeks,   were  examined.
Tires   of   the  first  model,   a   steel-belted radial,   were
manufactured  during  the  weeks  of  November  2-8,  1980,  and
February 8-14,   1981.  The difference between the means of these
two groups  is  0.00004 and the pooled standard  deviation (i.e.,
the  standard  deviation for  the entire  model)  of the model  is
0.00014.   Tires  of  the  second  model,  also  a  steel-belted
radial, were made  during  the weeks of May 9-15 and May  30-June
5, 1982.  The difference  between the means  of  these two groups
is 0.00023  and the pooled  standard deviation  is 0.00017.   The
means of the first model  were  not  different at  the 99  percent
confidence  level;  the  means  of  the   second   model  were  not
different  at  the  95  percent  confidence  level.  These  figures
are  very consistent for  the  two  models,  and  demonstrate that
the  rolling resistance of  a  tire could be relied upon  as  a
stable manufacturing parameter, based upon our testing.

-------
                        Table 9

              Mean RRC and Purchase Price
    Brand and Model
  RRC
 Price*
BF Goodrich Lifesaver
   XLM
Uniroyal Steeler
Delta Radial II
Laramie Glass Rider
Atlas Silveraire
Firestone Deluxe
   Champion Radial
Michelin XWW
Multi-Mile XL
Montgomery Ward Runabout
General Steel Radial
Uniroyal Tigerpaw
JC Penney Mi leagemaker
   Plus
Goodyear Arriva
Kelly-Springfield
   Navigator
General Dual Steel III
Multi-Mile Supreme
Goodyear Custom Poly-
   Steel
K-Mart KM-225
Dayton Quadra
Delta Durasteel
Firestone 721
Dayton Blue Ribbon
JC Mileagemaker XP
Firestone Trax 12
Summit Steel
Sears Road Handler 78
Dunlop Goldseal
Montgomery Ward Grap-
   pler
Sears Weather Handler
Goodyear Tiempo
Cooper Lifeliner (glass
  belt)
Armstrong SXA
Dunlop Generation IV
Cooper Lifeliner (steel
  belt)
0.00979

0.00997
0.01009
0.01018
0.01035
0.01041

0.01048
0.01052
0.01055
0.01059
0.01067
0.01078

0.01087
0.01087

0.01091
0.01097
0.01101

0.01104
0.01109
0.01110
0.01122
0.01149
0.01152
0.01167
0.01176
0.01177
0.01186
0.01208

0.01212
0.01227

0.01228
O.O1232
0.01249

0.01261
$ 49.94

  57.72
  47.60
  45.75
  57.03
  47.17

  86.59
  46.95
  80.08
  62.41
  54.39
  84.18

  67.13
  55.00

  69.59
  49.94
  57.98

  60.97
  39.47
  43.70
  62.17
  51 .64
  93.16
  55.44
  42.87
 117.49
  54.95
 109.08

  73.07
  61.63

  49.82
  61.14
  57.95

  54.44

-------
                   Table 9  (cont'd.)

              Mean RRC and Purchase Price
   Brand and Model

Michelin XVS
Goodyear Cushion Belt
   Polyglas
Armstrong Coronet All-
  Season
Kelly-Springfield
   Roadmark
Sears Super Guard
Goodyear Power Streak
Laramie Easy Rider
Firestone Deluxe
   Champion Bias-Ply
Montgomery Ward Road
   Guard
BF Goodrich Belted
   CLM
Sears Guardsman
Dayton Deluxe 78
Summit Supreme 120
K-Mart Economizer
Kelly-Springfield
   Benchmark
K-Mart KM-78
Cooper Trendsetter
Atlas Cushionaire
Multi-Mile Poly IV
Uniroyal Fastrak Poly
RRC
0.01363
0.01371
0.01381
0.01393

0.01409
0.01411
0.01428
0.01431

0.01433

0.01445

0.01468
0.01477
0.01546
0.01549
0.01558

0.01599
0.01624
0.01641
0.01644
0.01672
Price*

 $ 90.00
   45.04
   63.83
   41.00

   60.07
   41.25
   34.21
   40.84

   69.08

   38.48

   37.79
   28.62
   30.40
   34.97
   38.00

   41.00
   32.98
   28.00
   34.95
   41.19
 Prices given may not be representative of current prices.

-------
                      Table  10

     Rolling  Resistance  Consistency Over  Time -
Groups of Tires Manufactured During Different Weeks
Group 1
Group 2

Group 1
Group 2
Model
Date of
N Manufacture
2 Nov. 2-8, 1980
4 Feb. 8-14, 1981
Pooled standard
Model 2
Date of
N Manufacture
2 May 9-15, 1982
4 May 30-
1
RRC
0.00979
0.00975
deviation:
RRC
0.01086
0.01109
Standard
Deviation
0.00006
0.00018
0.00014
Standard
Deviation
0.00016
0.00012
              June 5,1982

           Pooled standard deviation:       0.00017

-------
                              -30-
     G.    Reliability

     To  further  determine how  reliably the  rolling resistance
of an  individual  tire from  a model  line  reflects  the  rolling
resistance of  the entire model line,  the  standard deviation of
the models were  examined.  The standard deviation  ranged  from
0.00006 to 0.00058, with  a  mean of 0.00022.  The coefficient of
variation  for  each  model  was  typically   2  percent.   The  90
percent  confidence  interval  about  the mean was  typically  only
+0.00035.  These  figures  signify  that the  sample  sizes  of  four-
and  six  were  adeguate  to  obtain  sound  statistics.    These
figures  also  indicate that  testing  only  one  tire  of  a  given
model gives a  good  indication of  the mean rolling resistance of
the model.

IX.  Quality Control

     Two tires (Michelin  XWWs)  served as correlation  tires  and
were each  tested seven  times  as a  means  of  checking  for  any
variations in  the test  results  as  a  function of  time.   Only
minute  changes in  the  test  results  were  observed  caused  by
time-dependent  factors  such  as  calibration   drifts,  lack  of
machine alignment, or  other unknown factors.   The RRC for these
tires  ranged  from  0.0105   -  0.0108.    The  pooled  standard
deviation of  these  tires' test results, for  test dates  ranging
from July  6,   1982  to March  15,   1984,  was  0.00009.   The  low
standard deviations for the models (given  on the previous page)
and  for  the  correlation  tires -reflect   precision  testing,
consistent  test   conditions,   and   again  demonstrates   the
predictability of rolling resistance  for an  individual  tire if
a tire of the same model has been tested.

X.   Conclusions

     A.    Summary of Results

     Based on  the  test  results  from  252 tire  tests,   it  was
determined that   the  following characteristics  influence  tire
rolling resistance:

     1.    Model
     2.    Construction
     3.    Body cord

Belt fiber was also observed to  have  some  influence on  rolling
resistance, but the  sample size  of  different  belt  fibers  and
the variation within this sample were small.

     It  was   concluded  that   neither  price  nor  date   of
manufacture (within a  reasonable  amount of time)   is  related to
a  tire's  rolling resistance.   Finally, an examination of  the
standard  deviations  from  all   models  tested  and  from   the
correlation   tires    showed   precise,   uniform   testing   and
demonstrated the  reliability  of the rolling  resistance  test to
forecast the  rolling  resistance  of  tire  models  by  testing an
individual tire of that model.

-------
                              -31-


     For   the  most   part,   the   lowest   rolling   resistance
characteristics  examined  were  actually present  in  the  test
tires which  received the  lowest rolling resistance.   That  is,
the  statistically  "best"  tires  generally  did  have the  lowest
rolling resistance values in the test program.

     Based  on  this  analysis,  the  most  fuel-efficient  tire
appears to be:

     1.     Radial-ply, and to have
     2.     Polyster body cords.

The three lowest rolling resistance models were:

     1.     BF Goodrich Lifesaver XLM
     2.     Uniroyal. Steeler
     3.     Delta Radial II.

All three of the above models were:

     1.     Radials,
     2.     Steel-belted with
     3.     Polyester body cord.

     Examination   of   the  predicted  best   tires  versus  the
observed  best tires  indicate  that  the  prediction  is  adeguate
for  the  major macroscopic  parameters  such  as construction type
and body cord.

     B.     Comparison with Previous Findings

     This  analysis agreed,  for  the  most   part,  with  earlier
findings.[3]    Both   studies   found  a  relationship   between
construction  type,  belt fiber,  and  manufacturer; both studies
also  found that tires  are manufactured consistently.   Neither
study found  a relationship between  purchase price  and rolling
resistance.    Table   11   summarizes    the   previous   study's
findings.   The  previous  study  did  not  find  a  correlation
between  body  cord and  rolling resistance, while  this  study
found  some  weak  correlation.   This   can,  most  likely,   be
attributed to the  substantially larger sample size used in this
analysis.

-------
                            Table 11
          Summary  of  Results  from  a Previous  Study[3]
      Effects  of Tire Characteristics On Rolling Resistance
     Tire
Characteristics

Manufacturer
Sample Used

86 tires from
  19 companies
Construction Type    13-inch tires
                     15-inch tires
Belt Fiber
13-inch
radials
Body Cord


Price
13-inch steel
radials

13-inch radials
                     13-inch bias-
                     belted
                     13-inch bias
                     ply
Result Observed	

Identity of the
manufacturer does
affect RRC.

Radials had 18.3%
lower mean RRC than
bias-belted
and bias-ply tires.

Radials had 27.5%
lower mean RRC than
bias-belted and
23.5% lower mean
RRC than bias-ply
tires.

Fiberglass had 4.7%
lower mean RRC than
steel, 10.1% lower
mean RRC than
aramid and 24.2%
lower RRC than
r ayon.

Does not affect RRC.
Price is not
linearly dependent
on rolling
resistance.

Price is not
linearly dependent
on rolling
resistance.

Price is not
linearly dependent
on rolling
resistance.

-------
                       Table 11 (cont'd.)
          Summary  of Results  from  a Previous Study[3]
      Effects  of Tire  Characteristics On Rolling Resistance
     Tire
Characteristics

RRC Consistency
Over Time
Sample Used

3 groups of one
model of bias ply
tire made on dif-
ferent dates
                     2 groups of one
                     model of fiber-
                     glass radial made
                     on different dates
Result Observed	

RRC of a model
does not
vary appreciably
with date of
manufacture.

RRC of a model does
not vary appreciably
with date of
manufacture.

-------
                              -34-
                           References

     1.    "Tire   Rolling    Resistance   and    Vehicle   Fuel
Consumption," Glenn  D.  Thompson  and  Marty Reineman,  U.S.  EPA,
SAE Paper No. 81068,  February 1981.

     2.    "The   Effects   of   Tire   Rolling   Resistance   on
Automotive Emissions  and Fuel Economy,"  Randy Jones  and Terry
Newell,  U.S. EPA Technical  Report  No.  EPA-AA-SDSB-80-7,  May
1980.

     3.    Rolling Resistance Measurements -  106  Passenger  Car
Tires,"   Gayle   Klemer,   U.S.    EPA  Technical   Report   No.
EPA-AA-SDSB-81-03, August 1981.

     4.    MTD 16th Annual  Facts/Directory,  Modern Tire Dealer,
Vol. 63, No.  1,  January 1982.

     5.    "Interim  Report   on   the   Characterization  of  the
Rolling Resistance of Aftermarket  Passenger Car  Tires," Terry
Newell, March 1983.

     6.    1981 Yearbook and  1980 Yearbook,  The Tire  and  Rim
Association,  Inc.

     7.    "The  Measurement   of  Passenger   Car  Tire  Rolling
Resistance,"  SAE Information Report J1270, October 1979.

-------
                  Appendix A

'EPA  Recommended  Practice  for  the  Determination
   of Tire Rolling Resistance Coefficients"

-------
  EPA Recommended Practice for Determination
   of Tire Rolling Resistance Coefficients
               Glenn Thompson
                 March 1980
             Amended August 1980
  Standards Development and Support Branch
    Emission Control Technology Division
Office of Mobile Source Air Pollution Control
     Office of Air, Noise and Radiation
    U.S. Environmental Protection Agency

-------
I.   Introduction

     Ibis  test procedure  determines  the  tire rolling  resistance
coefficient for &  free  rolling  tire at a steady  speed.   This pro-
cedure   conforms   to   the  SAE   Recommended  Practice,   Rolling
Resistance  Measurement  Procedure  for Passenger  Car Tires  -  SAE
J1269,  generally  adopting  the recommended  conditions  of J1269  as
the  required  standard  conditions.   The  SAE Recommended  Practice
J1269  and the  accompanying  SAE  Information report J1270  may  be
consulted for additional information.

II.  Teat Equipment

     The  test  equipment  required  is a tire  dynamometer  which mea-
sures the tire energy dissipative force as  the  tire  is driven by a
large cylindrical test wheel.

     A.    Tire Dynamometer

     The  test  dynamometer  shall  be a cylindrical surface  machine
of 67.23  in (1.7076m) diameter.   The  test machine shall  be  capable
of supplying  a force on the tire perpendicular  to  the  test  sur-
face, and shall be able to measure the transverse reaction forces
acting  on the  tire or  the  torque  necessary  to drive the  test
wheel.  During  this  process the  machine must be  capable of  main-
taining the test surface at  constant  speed.   The  width of the test
surface must exceed the width of  all  test tires,  and the test sur-
face shall be  coated  with  a medium coarseness  abrasive  (80 grit).
As an example, medium  grit 3M  Safety-Walk  represents a  satis-
factory surface.*

     1.    Test Machine  Alignment

     The direction of application of  the  tire load  must be normal
to the test surface within 0.03 deg (0.5 mrad).   The wheel  plan of
the tire  must  be  normal to the test  surface within 0.03 deg (0.5
mrad) and parallel to the  direction of  motion of  the test  surface
within 0.03 deg (0.5 mrad).

     2.    Test Machine  Control  Accuracy

     Exclusive of  perturbations induced by  the  tire and rim  non-
uniformities,  the  test  equipment  must  control  the  test variables
within, the following limits:

                 U.S.  Customary  Units    SI Units

Tire Load              5 Ibf               22 N
Surface Speed          1 mph              2  km/h
*    The manufacturer of this product is identified to clarify the
example and does not imply endorsement of  the  product.

-------
     3.    Test Machine Instrumentation Accuracy

     The  instrumentation  used for  readout and  recording of  test
data oust be accurate within the  following tolerances:

                 U.S. Customary Units    SI Units

Tire Load                2 Ibf             8 N
Surface Speed            0.5 mph            0.8 km/h
Spindle Force            0.1 Ibf            0.4 N
Loaded Radius            0.1 in            0.002 m

     B.    The Test Cell Requirements  .

     The primary requirement for the test  cell  is  that  the ambient
temperature be well controlled.  In addition, the  support services
of compressed air should be  available  for  tire  inflation as  should
the necessary gauges to measure tire Inflation.

     1.    Thermal Control

     The  ambient  temperature  in the  vicinity  of the  test  tire
shall be 75 + 5F (24 + 3"C).

     2.    Temperature Measurement Precision

     The  instrumentation  used to measure  the ambient  temperature
must be  accurate  to  within 1 F  (0.5 C).  This  instrumentation
shall  be  located  approximately 15  inches  from the tire, measured
perpendicular to the sidewall.

III. Test Procedure

     The  test  procedure  consists  of  the  following  steps:    tire
mounting; tire break-in; equilibration of  the tire  co the test am-
bient  temperature; adjustment of the cold  inflation pressure;  tire
warm-up and .hen measurement of the tire rolling resistance.

     A.    Tire Mounting

     1.    Rims

     The tire shall be mounted on test  rims which  have  an approved
contour  and  width  as specified  by the  Tire  & Rim Association,
Inc.,  as  "design  rim width" +_  one half  inch  for  the  size  cire
being  rested.  For  tire  sizes not standardized  by the  Tire &  Rio
Association,   Inc.,  reference  should be  made  to  the  appropriate
standardizing organization as listed in the Federal Motor Vehicle
Safety  Standards  (CFR  Title 49  571.109  Table  I).   These  rims
shall  have  a maximum  radial runout of  0.035 in  (0.88  mm)  and  a
maximum lateral runout of 0.045 in (1.1 mm).

-------
     2.    Inflation Pressure

     The Inflation pressure of the tires after mounting shall be:

     Alpha Numeric Size Tires            32 psi (220 IcPa)

     "P" Type tires                      35 psi (240 kPa)

The  tire  inflation  pressure  after mounting  shall  be correct  to
within 1 psi (6.8 kPa).  The  gauges  used to measure this  tire  in-
flation pressure shall be accurate to within 0.5 psi (3.4  kPa).

     B.    Tire Break-in

     Tires  may undergo  significant  permanent growth  upon  first
operation and  therefore  may  require  an initial break-in and  cool-
Ing  period  prior  to the start  of the  test.   A break-in  run con-
sisting of installing the tire on  the  tire  test machine and opera-
ting the system under  the  test conditions  for a period of  1 hour
is recommended.

     C.    Thermal Conditioning

     After initial  break-in  the  tire  shall be  placed  in  the ther-
mal environment of  the  test  conditions  for  a minimum period of  3
hours  before   the  test.   During  this  period  the  tire  inflation
pressure  should  be  checked  and  adjusted  if necessary,  to  the
design cold inflation pressure of the tire.

     D.    The Rolling Resistance Measurement

     The  test  consists  of   a  final  pressure  check,  loading  the
tire, the tire warm-up,  during which the tire  temperature and  in-
flation are allowed to  increase as they would  in  typical  service;
followed by the rolling resistance measurement.

     1.    Installation on the Test Machine

     The inflation  pressure  of the tire shall be checked  and  ad-
Justed if necessary.   The  inflation  pressure  immediately  prior  to
the  test  shall  be  correct  to within 0.25  psi  (1.7  kPa).   The
gauges used to determine this  pressure  shall  be accurate  to within
0.25 psi (1.7  kPa).  The tire  shall  then be  installed  on  'the  test
machine if  not already installed, and the load  on the tire  per-
pendicular to  the  test surface shall  be adjusted to 80 percent  of
the design load of the tire.

     2.    Tire Warm-up

     The test  tire shall be conditioned  by  operation at a  speed  of
50 mph for a minimum of 45 minutes.

-------
     Tx - the test wheel drive torque of  III D3.

     Tp  the parasitic test wheel drive  torque of  III D4.

     B.    Tire Energy Dissipation Force

     The  tire  energy dissipation  force  shall be  calculated  from
the net spindle reaction force by the following equation:
     Fd  f(l + r/R)                                            (2)

Where t

     Fd - the tire energy dissipation -force Ib (N),

     F  - the net tire spindle force Ib (N),

     r  = the tire loaded radius ,  in (a) ,

     R   the test surface radius, in (m).

     la the case  of  the  torque measurement method the energy  dis-
sipation force is to be calculated by:

     Fd - T/R                                                   (3)

     3.    Rolling Resistance Measurements

     Following  the  tire  warm-up  and with  the  test dynamometer
operating at 50 mph, the following parameters shall  be recorded:

     a.    Tire spindle force or test wheel drive  torque.
     b.    Normal load on the tire.
     c.    Loaded radius of the tire.

     4.    Measurement of Parasitic Losses

     As a final measurement, the  parasitic machine losses  shall  be
determined.  The  test  machine  speed shall  be maintained at  50 mph
while  the  load  onthe tire is reduced to approximately one percent
of the  test  load.  Under  this  condition  the following  parameters
shall be determined:

     a.    Tire spindle( force or test sheel drive  torque.
     b.    Normal load on the tire.

IV.  Data Analysis

     The data reduction consists of  the correction for the machine
parasitic  losses,  conversion  to a  tire  energy dissipation  force,
correction to  the standard test  temperature,  and the computation
of the tire rolling resistance coefficient.

-------
     A.    Subtraction of Parasitic Losses

     The spindle  force  or test wheel  drive  torque measurement  of
the  machine  parasitic  losses  obtained  in  III.   D4,   shall  be
subtracted  from the  spindle  forces or  test  wheel  drive  torques
measured  during  the  test,  III'  D3,  to  obtain the  net  spindle
reaction force or net drivewheel drive  torque.

That is:

     F - Fx - Fp                                                (1)

     T - Tx - Tp

Where t

     F  -   the net spindle reaction force.

     Fx -   the spindle  reactive  force measured  during  the  test,
            III. D3.

     Fp *   the parasitic spindle reactive force of  III.  D4.

     I     the net test wheel drive torque.

     C.    Temperature Correction

     The tire  energy  dissipation force shall  be  corrected to  the
standard test temperature of 7SF by the following equation:

     Fd* - Fd[l + ct(tx - ts)]                                  (4)

     F,j*   the tire  dissipative force  at  the standard  tempera-
ture ,

     tx  -  the average measured temperature over  the duration  of
the test,

     ts . = the standard test temperature 75F (24C),

     ct  -  the temperature correction  coefficient,  5  x  10~^/F
(9 x 10~3/8C).

     The test ambient temperature shall always  be within  75  + 5F
(24  +- 3C),   as  described  in  II.B.l.;  therefore,   this  linear
temperature correction will  always  be  applied over a temperature
range of less than 5F (3C) for any one test.

     D.    Net Load Force

     The parasitic  load force  measured in  III D4 shall  be  sub-
tracted from  the  normal  load  force  measured  during the test  IIID3
to obtain the net  load force.

-------
That 1st

     L - L, - Lp                                                (5)

Where*

     L  - the net  load  force,

     LX * the tire load force measured during the test III D3.

     Lp  -  the tire  load  force during  the parasitic  measurement
III D4.

     E.    Rolling Resistance Coefficient

     The rolling  resistance coefficient is  calculated  by dividing
the energy dissipation  force by the net load imposed in the tires

     C - Fd*/L                                                 (6)

Where t

     C * rolling resistance coefficient (RRC)".

     Equations 1,  2,  4, 5,  and 6 may be combined  into  the follow-
ing single equation:

        (F* - VCl
     C
                        -v
     Likewise,  equations 1, 3, 4, 5, and 6 may be combined as:

      _ 
-------
                   Appendix B




Individual Tire Rolling Resistance Test Results

-------
Rolling Resistance Test Results for Individual Tires
EPA ID#
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
Mfr/Brand
& Model
Armstrong Coronet All-
Season Radial
Armstrong Coronet All-
Season Radial
Armstrong Coronet All-
Season Radial
Armstrong Coronet All-
Season Radial
Armstrong SXA Radial
Armstrong SXA Radial
Armstrong SXA Radial
Armstrong SXA Radial
Atlas Cushionaire Bias
Atlas Cushionaire Bias
Atlas Cushionaire Bias
Atlas Cushionaire Bias
Atlas Silveraire Radial
Atlas Silveraire Radial
Test Date
10/27/82
10/27/82
10/28/82
10/28/82
10/27/82
10/27/82
10/27/82
10/27/82
9/15/82
9/15/82
9/16/82
9/16/82
9/23/83
9/29/83
RR Force
(Ibf)
15.62
15.29.
15.50
15.50
13.77
13.90
13.76
13.77
18.47
19.05
17.86
18.20
11.56
11.56
Ambient
RRC Temp. (F)
0.01392
0.01362
0.01385
0.01386
0.01228
0.01239
0.01230
0.01232
0.01648
0.01699
0.01592
0.01624
0.01031
0.01029
74
78
75
77
74
75
75
75
75
74
73
78
77
73
Temperature-Corrected
RR Force (Ibf) RRC
15.57
15.44
15.50
15.60
13.72
13.90
13.76
13.77
18.47
18.99
17.74
18.38
11.64
11.48
0.01388
0.01375
0.01385
0.01396
0.01224
0.01239
0.01230
0.01232
0.01648
0.01694
0.01581
0.01640
0.01038
0.01023

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Rolling Resistance Test Results for Individual Tires
EPA ID#
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
Mfr/Brand
& Model
Atlas Silveraire
Atlas Silveraire
Cooper Lifeliner
(Glass belt)
Cooper Lifeliner
(Glass belt)
Cooper Lifeliner
(Glass belt)
Cooper Lifeliner
(Glass belt)
Cooper Lifeliner
(Steel belt)
Cooper Lifeliner
(Steel belt)
Cooper Lifeliner
(Steel belt)
Cooper Lifeliner
(Steel belt)

Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Cooper Trendsetter
Cooper Trendsetter
Test Date
9/29/83
9/29/83
10/19/82
10/19/82
10/19/82
10/19/82
10/15/82
10/15/82
10/19/82
10/19/82
10/01/82
10/05/82
RR Force
(Ibf)
11.
11.
13.
13.
13.
13.
14.
14.
13.
14.
18.
17.
63
69
70
75
82
76
34
21
88
09
94
71
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.

Ambient
Temperature-Corrected
RRC Temp. (F) RR Force (Ibf) RRC
01035
01045
01221
01230
01232
01229
01277
01268
01238
01259
01687
01577
78
75
78
77
78
72
77
77
75
77
78
77
11
11
13
13
13
13
14
14
13
14
19
17
.75
.69
.84
.84
.96
.62
.43
.30
.88
.18
.13
.83
0.01045
0.01045
0.01233
0.01238
0.01244
0.01216
0.01285
0.01276
0.01238
0.01267
0.01703
0.01587

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Rolling Resistance Test Results for Individual Tires
EPA ID#
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
Mfr/Brand
& Model
Cooper
Cooper
Dayton
Dayton
Dayton
Dayton
Dayton
Dayton
Dayton
Dayton
Dayton
Dayton
Dayton
Dayton
Trendsetter
Trendsetter
Blue Ribbon
Blue Ribbon
Blue Ribbon
Blue Ribbon
Deluxe 78 Bias
Deluxe 78 Bias
Deluxe 78 Bias
Deluxe 78 Bias
Quadra Radial
Quadra Radial
Quadra Radial
Quadra Radial
Delta Durasteel
Delta Durasteel
Test Date
10/07/82
10/07/82
10/21/82
10/21/82
10/21/82
10/21/82
10/25/82
10/25/82
10/25/82
10/25/82
10/25/82
10/25/82
10/26/82
10/26/82
10/14/82
10/14/82
RR Force
(Ibf)
17.
18.
12.
12.
12.
12.
16.
16.
16.
16.
12.
12.
12.
12.
12.
12.
88
29
71
99
78
99
41
53
67
60
47
66
40
12
58
37
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
Ambient
RRC Temp. (F)
01599
01632
01135
01159
01142
01162
01468
01472
01486
01481
01113
01128
OHIO
01082
01122
01102
77
75
73
74
74
73
78
76
76
79
75
76
75
76
75
75
Temperature-Corrected
RR Force (Ibf) RRC
18.
18.
12.
12.
12.
12.
16.
16.
16.
16.
12.
12.
12.
12.
12.
12.
00
29
63
95
74
90
57
58
73
82
47
70
40
16
58
37
0.01610
0.01632
0.01127
0.01155
0.01138
0.01154
0.01482
0.01477
0.01491
0.01500
0.01113
0.01132
0.01110
0.01086
0.01122
0.01102

-------
Rolling Resistance Test Results for Individual Tires
EPA ID#
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
Mfr/Brand
& Model
Delta Durasteel
Delta Durasteel
Delta Padial II
Delta Radial II
Delta Radial II
Delta Radial II
Dunlop Generation IV
Dunlop Generation IV
Dunlop Generation IV
Dunlop Generation IV
Dunlop Goldseal
Dunlop Goldseal
Dunlop Goldseal
Dunlop Goldseal
Firestone 721
Firestone 721
Test Date
10/14/82
10/14/82
10/13/82
10/13/82
10/13/82 ,
10/13/82
9/14/82
9/14/82
9/14/82
9/14/82
5/27/83
5/27/83
5/27/83
5/27/83
9/16/83
9/16/83
RR Force
dbf)
12.57
12.31
11.23
11.37
11.57
11.02
13.70
13.96
14.51
13.82
13.47
13.13
13.19
13.34
12.70
12.29
Ambient
RRC Temp. (F)
0.01120
0.01096
0.01004
0.01015
0.01031
0.00984
0.01221
0.01248
0.01294
0.01233
0.01205
0.01170
0.01179
0.01192
0.01130
0.01099
74
74
78
77
75
78
75
75
74
76
76
74
74
75
73
75
Temperature-Corrected
RR Force (Ibf ) RRC
12.53
12.27
11.34
11.45
11.57
11.13
13.70
13.96
14.46
13.87
13.51
13.09
13.15
13.34
12.62
12.29
0.01117
0.01093
0.01014
0.01022
0.01031
0.00994
0.01221
0.01248
0.01290
0.01237
0.01209
0.01166
0.01175
0.01192
0.01122
0.01099

-------
              Rolling Resistance Test Results for Individual Tires
EPA IDt
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
Mfr/Brand
& Model
Firestone 721
Firestone 721
Firestone 721
Firestone 721
Firestone Deluxe
Champion Radial
Firestone Deluxe
Champion Radial
Firestone Deluxe
Champion Radial
Firestone Deluxe
Champion Radial
Firestone Deluxe
Champion Radial
Firestone Deluxe
Champion Radial
Firestone Deluxe
Champion Bias
Firestone Deluxe
Test Date
9/16/83
9/16/83
9/16/83
9/16/83
9/16/83
9/16/83
9/22/83
9/22/83
9/22/83
9/22/83
9/22/83
9/22/83
RR Force
(Ibf)
12.42
12.49
12.83
12.77
11.71
11.51
11.85
11.44
12.07
11.45
16.10
16.16
Ambient
RRC Temp. (F)
0.01112
0.01111
0.01141
0.01137
0.01047
0.01025
0.01059
0.01022
0.01076
0.01020
0.01435
0.01445
75
78
74
.76
73
74
78
74
76
77
78
78
Temperature-Corrected
RR Force (Ibf) RRC
12.42
12.61
12.79
12.81
11.63
11.47
11.97
11.40
12.11
11.53
16.26
16.32
0.01112
0.01122
0.01138
0.01141
0.01040
0.01022
0.01069
0.01019
0.01079
0.01026
0.01449
0.01460
Champion Bias

-------
Rolling Resistance Test Results for Individual Tires
EPA IDt
4171
4172
4173
4174
4175
4176
4185
4186
4187
4188
4189
4190
4191
4192
4193
Mfr/Brand
& Model
Firestone Deluxe
Champion Bias
Firestone Deluxe
Champion Bias
Firestone Trax 12
Firestone Trax 12
Firestone Trax 12
Firestone Trax 12
General "Steel" Radial
General "Steel" Radial
General "Steel" Radial
General "Steel" Radial
General "Steel" Radial
General "Steel" Radial
General Dual Steel III
General Dual Steel III
General Dual Steel III
Test Date
9/22/83
9/23/83
9/23/83
9/23/83
9/23/83
9/23/83
9/29/83
9/29/83
9/29/83
9/29/83
9/29/83
9/30/83
6/16/83
6/16/83
6/16/83
RR Force
(Ibf)
15.62
16.28
12.62
12.55
12.42
.12.47
11.82
12.64
11.69
11.81
11.68
11.48
12.44
12.37
12.43
RRC
0.01392
0.01451
0.01128
0.01119
0.01108
0.01112
0.01058
0.01128
0.01043
0.01054
0.01044
0.01026
0.01110
0.01105
0.01110
Ambient
Temp. (F)
79
76
78
75
79
76
78
79
74
78
75
77
77
75
75
Temperature-Corrected
RR Force (Ibf)
15.83
16.33
12.74
12.55
12.58
12.51
11.94
12.81
11.65
11.93
11.68
11.56
12.52
12.37
12.43
RRC
0.01411
0.01456
0.01139
0.01119
0.01123
0.01116
0.01069
0.01142
0.01039
0.01064
0.01044
0.01033
0.01117
0.01105
0.01110

-------
             Rolling Resistance Test Results for Individual Tires
EPA ID#
4194
4195
4196
4197
4198
4199
4200
4201
4202
4209
4210
4211
4212
4213
Mfr/Brand
& Model
General Dual Steel III
General Dual Steel III
General Dual Steel III
BF
BF
BF
BF
BF
BF
BF
BF
BF
BF
BF
Goodrich
Goodrich
Goodrich
Goodrich
Goodrich
Goodrich
Goodrich
XIM
Goodrich
XIM
Goodrich
XIM
Goodrich
XIM
Goodrich
CIM
CIM
CIM
CIM
CIM
OM
Lifesaver
Lifesaver
Lifesaver
Lifesaver
Lifesaver
Test Date
6/16/83
6/16/83
6/16/83
6/16/83
6/17/83
6/17/83
6/17/83
6/20/83
6/20/83
6/20/83
6/20/83
6/20/83
6/20/83
6/20/83
RR Force
dbf)
11.68
12.15
12.24
16.15
16.23
16.30
16.01
16.15
16.22
11.27
10.68
10.82
11.02
11.01
Ambient
RRC Temp. (F)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
.01045
.01083
.01095
.01443
.01448
.01455
.01432
.01442
.01450
.01004
.00952
.00967
.00986
.00985
72
74
75
79
78
75
77
74
74
73
76
77
73
72
Temperature-Corrected
RR Force (Ibf) RRC
11
12
12
16
16
16
16
16
16
11
10
10
10
10
.56
.11
.24
.36
.39
.30
.12
.10
.17
.20
.72
.89
.95
.90
0.01034
0.01079
0.01095
0.01462
0.01462
0.01455
0.01441
0.01437
0.01445
0.00998
0.00955
0.00973
0.00979
0.00975
XIM

-------
             Rolling Resistance Test Results for Individual Tires
Mfr/Brand
EPA ID# & Model
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
BF Goodrich Lifesaver
XIM
Goodyear Arriva
Goodyear Arriva
Goodyear Arriva
Goodyear Arriva
Goodyear Arriva
Goodyear Arriva
Goodyear Cushion Belt
Polyglas
Goodyear Cushion Belt
Polyglas
Goodyear Cushion Belt
Polyglas
Goodyear Cushion Belt
Polyglas
Goodyear Cushion Belt
Polyglas
Goodyear Cushion Belt
Test Date
6/20/83
6/21/83
6/21/83
6/21/83
6/21/83
6/21/83
6/21/83
6/21/83
6/21/83
6/21/83
6/21/83
6/21/83
6/21/83
RR Force
(Ibf)
10.95
11.85
12.33
12.06
12.53
12.06
12.12
15.13
15.32
15.39
15.26
15.61
15.39
Ambient
RRC Temp. (F)
0.00980
0.01059
0.01104
0.01082
0.01121
0.01075
0.01080
0.01353
0.01370
0.01374
0.01364
0.01393
0.01372
76
73
73
75
76
75
75
73
75
73
77
73
75
Temperature-Corrected
RR Force (Ibf) RRC
10.99
11.77
12.25
12.06
12.57
12.06
12.12
15.03
15.32
15.29
15.36
15.51
15.39
0.00984
0.01052
0.01097
0.01082
0.01124
0.01075
0.01080
0.01344
0.01370
0.01365
0.01373
0.01383
0.01372
Polyglas

-------
Rolling Resistance Test Results for Individual Tires
EPA IDf
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
Mfr/Brand
& Model
Goodyear Custom
Polysteel
Goodyear Custom
Polysteel
Goodyear Custom
Polysteel
Goodyear Custom
Polysteel
Goodyear Custom
Polysteel
Goodyear Custom
Polysteel
Goodyear Power Streak
Goodyear Power Streak
Goodyear Power Streak
Goodyear Power Streak
Goodyear Power Streak
Goodyear Power Streak
Goodyear Tiempo
Test Date
6/21/83
6/21/83
6/22/83
6/22/83
6/22/83
6/22/83
6/22/83
6/22/83
6/22/83
6/22/83
6/22/83
6/22/83
6/22/83
RR Force
(Ibf)
12.29
12.09
12.29
12.50
12.56
12.29
16.07
15.41
15.99
15.25
16.06
16.05
13.36
Ambient
RRC Temp. (F)
0.01097
0.01079
0.01094
0.01117
0.01120
0.01095
0.01432
0.01372
0.01426
0.01358
0.01438
0.01437
0.01195
75
74
77
74
76
76
78
76
79
77
79
76
73
Temperature-Corrected
RR Force (Ibf) RRC
12.29
12.05
12.37
12.46
12.60
12.33
16.23
15.46
16.20
15.35
16.27
16.10
13.27
0.01097
0.01075
0.01102
0.01113
0.01124
0.01099
0.01446
0.01377
0.01445
0.01367
0.01457
0.01442
0.01187

-------
                          Rolling Resistance Test Results for Individual Tires
EPA ID#
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
Mfr/Brand
& Model
Goodyear Tiempo
Goodyear Tiempo
Goodyear Tierrpo
Goodyear Tiempo
Goodyear Tiempo
Laramie Easy Rider
Laramie Easy Rider
Laramie Easy Rider
Laramie Easy Rider
Laramie Glass Rider
Laramie Glass Rider
Laramie Glass Rider
Laramie Glass Rider
Kelly-Spr ingf ield
Test Date
6/22/83
6/22/83
6/22/83
6/22/83
6/23/83
10/26/82
10/26/82
10/26/82
10/26/82
10/26/82
10/26/82
10/27/82
10/27/82
4/07/83
RR Force
dbf)
14.24
13.63
13.49
13.70
14.04
16.10
15.81
15.41
16.66
11.54
11.46
11.34
11.27
17.38
Ambient
RRC Temp. (F)
0.01269
0.01216
0.01208
0.01221
0.01254
0.01436
0.01414
0.01373
0.01486
0.01029
0.01026
0.01013
0.01004
0.01549
73
72
73
76
74
77
76
72
74
72
75
75
76
76
Temperature-Corrected
RR Force (Ibf) RRC
14.15
13.50
13.40
13.75
13.99
16.21
15.86
15.26
16.61
11.43
11.46
11.34
11.31
17.44
0.01261
0.01204
0.01200
0.01225
0.01249
0.01446
0.01419
0.01360
0.01481
0.01018
0.01026
0.01013
0.01008
0.01554
             Benchmark

4254      Kelly-Springfield
             Benchmark
4/07/83
17.65
0.01577
77
17.77
0.01588

-------
Rolling Resistance Test Results for Individual Tires
EPA ID|
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
Mfr/Brand
& Model
Kelly-Springfield
Benchmark
Kelly-Spr ingf ield
Benchmark
Kelly-Spr ingf ield
Navigator
Kelly-Spr ingf ield
Navigator
Kelly-Spr ingf ield
Navigator
Kelly-Spr ing f ield
Navigator
Kelly-Spr ingf ield
Roadmark
Kelly-Spr ingf ield
Roadmark
Kelly-Spr ingf ield
Roadmark
Kelly-Spr ingf ield
Roadmark
K-Mart Economizer
Test Date
4/08/83
4/08/83
5/27/83
5/27/83
6/14/83
6/15/83
4/08/83
4/08/83
4/11/83
5/26/83
10/15/82
RR Force
(Ibf)
17.88
15.94
12.23
11.89
12.50
12.09
15.23
15.91
15.83
15.49
17.16
Ambient
RRC Temp. (F)
0.01594
0.01514
0.01092
0.01061
0.01115
0.01080
0.01360
0.01419
0.01410
0.01383
0.01529
77
76
72
73
73
74
75
73
75
77
78
Temperature-Oor r ec ted
RR Force (Ibf) RRC
18.00
15.99
12.11
11.81
12.42
12.05
15.23
15.80
15.83
15.59
17.33
0.01604
0.01519
0.01081
0.01054
0.01108
0.01077
0.01360
0.01410
0.01410
0.01392
0.01545

-------
Rolling Resistance Test Results for Individual Tires
EPA ID#
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
Mfr/Brand
& Model
K-Mart Economizer
K-Mart Economizer
K-Mart Economizer
K-Mart KM225
K-Mart KM225
K-Mart KM225
K-Mart KM225
K-Mart KM-78
K-Mart KM-78
K-Mart KM-78
K-Mart KM-78
Michelin XWW
Michelin XWW
Michelin XWW
Michelin XWW
Michelin XWW
Test Date
10/15/82
10/15/82
10/15/82
10/12/82
10/12/82
10/12/82
10/13/82
10/20/82
10/20/82
10/20/82
10/20/82
7/06/82
7/06/82
9/25/82
9/26/82
9/26/82
RR Force
(Ibf)
17.33
17.47
17.42
12.28
12.69
12.28
12.22
18.00
17.65
18.15
17.88
11.89
11.89
11.69
11.68
11.68
Ambient
RRC Temp. (F)
0.01550
0.01561
0.01554
0.01093
0.01133
0.01094
0.01093
0.01606
0.01573
0.01622
0.01596
0.01061
0.01061
0.01040
0.01042
0.01043
77
75
78
76
75
75
78
75
76
76
73
76
76
76
75
75
Temperature-Corrected
RR Force (Ibf) RRC
17.44
17.47
17.59
12.32
12.69
12.28
12.34
18.00
17.71
18.21
17.76
11.93
11.93
11.73
11.68
11.68
0.01560
0.01561
0.01569
0.01097
0.01133
0.01094
0.01104
0.01606
0.01578
0.01627
0.01586
0.01064
0.01064
0.01043
0.01042
0.01043

-------
             Rolling Resistance Test Results for  Individual Tires
EPA IDtt
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
Mfr/Brand
& Model
Michel in XWW
Michelin XVS
Michel in XVS
Michelin XVS
Michelin XVS
Montgomery Ward
Grappler All-Season
Montgomery Ward
Grappler All -Season
Montgomery Ward
Grappler All-Season
Montgomery Ward
Grappler All-Season
Montgomery Ward
Road Guard
Montgomery Ward
Road Guard
Montgomery Ward
Test Date
9/26/82
9/23/82
9/23/82
9/25/82
9/23/82
6/15/83
7/06/82
7/06/82
7/06/82
7/13/82
7/13/82
7/13/82
RR Force
(Ibf)
11.68
14.75
14.61
14.54
14.54
13.93
13.77
13.90
14.31
16.16
16.16
15.76
RRC
0.01041
0.01381
0.01368
0.01358
0.01354
0.01245
0.01228
0.01240
0.01277
0.01442
0.01440
0.01406
Ambient
Temp. (F)
7?
76
76
77
77
78
78
79
80
78
79
77
Temperature-Corrected
RR Force (Ibf)
11.76
14.80
14.66
14.64
14.64
14.07
13.91
14.08
14.55
16.32
16.37
15.86
RRC
0.01048
0.01386
0.01372
0.01367
0.01363
0.01257
0.01241
0.01256
0.01298
0.01456
0.01459
0.01415
Road Guard

-------
Rolling Resistance Test Results for Individual Tires
EPA ID#
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
Mfr/Brand
& Model
Montgomery Ward
Road Guard
Montgomery Ward
Runabout All-Season
Montgomery Ward
Runabout All -Season
Montgomery Ward
Runabout All-Season
Montgomery Ward
Runabout All-Season
Michelin XVS
Michelin XVS
Multi-Mile Poly IV
Multi-Mile Poly IV
Multi-Mile Poly IV
Multi-Mile Poly IV
Multi-Mile Supreme
Multi-Mile Supreme
Multi-Mile Supreme
Test Date
7/13/82
7/07/82
7/08/82
7/08/82
7/08/82
9/23/82
9/25/82
9/15/82
9/14/82
9/14/82
9/14/82
9/13/82
9/13/82
9/13/82
RR Force
(Ibf)
16.22
11.86
11.73
12.06
11.72
14.47
14.61
18.47
18.48
18.41
18.29
12.24
12.51
12.24
Ambient
RRC Temp. (F)
0.01446
0.01056
0.01045
0.01075
0.01045
0.01351
0.01364
' 0.01648
0.01651
0.01642
0.01634
0.01092
0.01116
0.01095
77
78
75
75
76
78
75
73
78
78
77
78
78
74
Temperature-Corrected
RR Force (Ibf) RRC
16.33
11.98
11.73
12.06
11.76
14.61
14.61
18.35
18.66
18.59
18.41
12.36
12.63
12.20
0.01455
0.01067
0.01045
0.01075
0.01048
0.01364
0.01364
0.01637
0.01668
0.01659
0.01645
0.01103
0.01127
0.01091

-------
Rolling Resistance Test Results for Individual Tires
EPA ID#
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
Mfr/Brand
& Model
Multi-Mile Supreme
Multi-Mile XL
Multi-Mile XL
JC
JC
JC
JC
JC
JC
JC
JC
Penney
XP
Penney
XP
Penney
XP
Penney
XP
Penney
Plus
Penney
Plus
Penney
Plus
Penney
Plus
Mileagemaker
Mileagemaker
Mileagemaker
Mileagemaker
Mileagemaker
Mileagemaker
Mileagemaker
Mileagemaker
Sears Guardsman
Test Date
9/13/82
9/15/82
9/15/82
7/08/82
7/08/82
7/08/82
7/08/82
7/06/82
7/07/82
7/07/82
7/07/82
7/09/82
RR Force
dbf)
12.11
11.56
11.64
13.12
12.58
12.98
12.98
11.92
12.13
11.99
12.26
16.78
Ambient
RRC Temp. (F)
0
0
0
0
0
0
0
0
0
0
0
0
.01083 .
.01033
.01040
.01170
.01122
.01157
.01157
.01065
.01081
.01069
.01097
.01500
77
76
74
78
76
76
76
78
77
76
76
77
Temperature-Corrected
RR Force (Ibf ) RRC
12.
11.
11.
13.
12.
13.
13.
12.
12.
12.
12.
16.
19
60
60
25
62
02
02
04
21
03
30
89
0.01090
0.01036
0.01037
0.01182
0.01126
0.01161
0.01161
0.01076
0.01088
0.01072
0.01100
0.01509

-------
Rolling Resistance Test Results for Individual Tires
EPA ID#
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
Mfr/Brand
& Model
Sears Guardsman
Sears Guardsman
Sears Guardsman
Sears Guardsman
Sears Guardsman
Sears Road Handler 78
Sears Road Handler 78
Sears Road Handler 78
Sears Road Handler 78
Sears Road Handler 78
Sears Road Handler 78
Sears Super Guard
Sears Super Guard
Sears Super Guard
Sears Super Guard
Sears Super Guard
Test Date
7/09/82
7/09/82
7/09/82
7/09/82
7/09/82
7/09/82
7/13/82
7/13/82
7/13/82
7/13/82
7/13/82
7/08/82
7/08/82
7/08/82
7/09/82
7/09/82
RR Force
dbf)
16.38
16.65
15.55
16.86
16.51
13.03
13.16
13.17
13.17
13.30
13.23
15.86
15.99
15.30
15.86
15.78
Ambient
RRC Temp. (F)
0.01464
0.01484
0.01387
0,01504
0.01471
0.01162
0.01174
0.01177
0.01179
0.01185
0.01182
0.01414
0.01424
0.01365
0.01414
0.01408
77
77
78
77
78
78
75
76
77
76
77
77
78
78
77
79
Temperature-Corrected
RR Force (Ibf) RRC
16.49
16.76
15.70
16.97
16.67
13.16
13.16
13.21
13.26
13.34
13.32
15.96
16.15
15.45
15.96
15.99
0.01473
0.01494
0.01401
0.01514
0.01486
0.01174
0.01174
0.01181
0.01187
0.01189
0.01190
0.01423
. 0.01438
0.01378
0.01423
0.01426

-------
Rolling Resistance Test Results for Individual Tires
EPA ID#
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
Mfr/Brand
& Model
Sears Super Guard
Sears Weather Handler
Sears Weather Handler
Sears Weather Handler
Sears Weather Handler
Sears Weather Handler
Sears Weather Handler
Multi-Mile XL
Multi-Mile XL
Summit Steel
Summit Steel
Summit Steel
Summit Steel
Summit Supreme 120
Summit Supreme 120
Summit Supreme 120
Test Date
7/09/82
7/07/82
7/07/82
7/07/82
7/07/82
7/07/82
7/07/82
9/15/82
9/15/82
10/12/82
10/12/82
10/12/82
10/12/82
10/07/82
10/07/82
10/07/82
RR Force
(Ibf)
15.99
13.73
13.26
13.87
13.66
13.79
13.26
12.11
11.83
13.43
12.68
13.15
13.43
16.98
17.29
17.33
Ambient
RRC Temp. (F)
0.01430
0.01225
0.01182
0.01237
0.01219
0.01230
0.01181
0.01080
0.01054
0.01196
0.01132
0.01175
0.01202
0.01519
0.01545
0.01550
76
78
79
77
77
77
78
77 .
76
75
74
74
75
74
73
79
Temperature-Corrected
RR Force (Ibf) RRC
16.04
13.87
13.44
13.96
13.75
13.88
13.39
12.19
11.87
13.43
12.64
13.11
13.43
16.92
17.18
17.56
0.01435
0.01237
0.01197
0.01245
0.01227
0.01238
0.01192
0.01087
0.01058
0.01196
0.01128
0.01171
0.01202
0.01514
0.01535
0.01571

-------
Rolli
P^c^nre Test Results  for Individual Tires

EPA ID#
4352
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
Mfr/Brand
&ii-J f kl
Model
Summit Supreme 120
Uniroyal Fastrak Poly
Uniroyal Fastrak Poly
Uniroyal Fastrak Poly
Uniroyal Fastrak Poly
Uniroyal Steeler
Uniroyal Steeler
Uniroyal Steeler
Uniroyal Steeler
Uniroyal Steeler
Uniroyal Steeler
Uniroyal Tiger Paw
Uniroyal Tiger Paw
Uniroyal Tiger Paw
Uniroyal Tiger Paw
Test Date

10/07/82
12/09/83
12/09/83
12/09/83
12/09/83
6/23/83
6/23/83
6/23/83
i
6/23/83
6/23/83
6/23/83
6/23/83
6/24/83
6/24/83
6/24/83
RR Force
(Ibf)

17.60
17.83
18.78
18.66
19.58
11.18
11.50
10.76
11.65
10.44
11.38
11.77
11.79
11.78
12.39
RRC

0.01569
0.01596
0.01683
0.01665
0.01744
0.01000
0.01026
0.00962
0.01043
0.00933
0.01018
0.01054
0.01054
0.01053
0.01106
Ambient
Temp. (F)
T1
77
75
-i/\
70
75
H *
74
76
*~ifl
77
M 1
75
n
77
78
77
78
73
77
75
Temperature-Cc
RR Force (Ibf)
17 72
J. t  / *-
17 8^
i /  o j
18 47
_LU  ^ '
1 ft fifi
J_O v/v
1Q S2
j_ ^  -/*
U22
 .
US8
 -^v
10 76
J_V/  / VJ
U73
 /  *
in S4
JLU . J^
U46
. *tv
URQ
. oy
U71
 / J-
11 86
J 	 L . U\J
i 9 oq
J.^. j"
)rrectea
RRC
0.01579
0.01596
0.01655
0.01665
0.01738
0.01003
0.01033
0.00962
0.01050
0.00942
0.01025
0.01064
0.01047
0.01060
0.01106


-------