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
-------
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
-------
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 70°F and 80°F, 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:
70-80°F. All tests in this program were conducted within this
temperature range, and the rolling resistance corrected to
standard temperature (75°F) 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
-------
Fd* = Fd [1 + ct (tx - t,)], (3)
where:
Fd* = temperature-corrected rolling resistance force
Fd = uncorrected rolling resistance force
t, = the standard test temperature (75°F)
tx = the measured test ambient temperature
ct = the temperature correction coefficient
(3.3xlO"V°F) .
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.
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-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.
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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 + 5°F (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 7S°F 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 75°F (24°C),
ct - the temperature correction coefficient, 5 x 10~^/°F
(9 x 10~3/8C).
The test ambient temperature shall always be within 75° + 5°F
(24 +- 3°C), as described in II.B.l.; therefore, this linear
temperature correction will always be applied over a temperature
range of less than 5°F (3°C) 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
-------
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
-------
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
------- |