^SmartWay5
    Transport Partnership
    U.S. ENVIRONMENTAL PROTECTION AGENCY
                              A Glance at
           Clean Freight Strategies
Single Wide-Based  Tires
 Specifying single wide-base tires on a new combination truck could save $1,000 initially, and cut over four metric
 tons of greenhouse gas emissions per year. Fuel savings of 2% or higher begin immediately.
 What is the challenge?
 Tire rolling resistance  accounts for nearly 13% of
 truck energy use. Most combination trucks have dual
 tire assemblies on the drive and trailer axles, with two
 sets of wheels and tires at each end of an axle. This
 configuration increases rolling resistance and weight,
 compared to single wide-base tires and wheels.


 What is the solution?
 A variety  of  tire options can improve truck fuel
 efficiency. One promising strategy is to use single
 wide-base tires. A single wide-base tire and wheel is
 lighter than two  standard tires and wheels.  Total
 weight savings for a typical combination truck using
 single wide-base tires on its drive and trailer axles
 ranges from  800 to  1,000  pounds.  The weight
 savings would reduce fuel consumption, or increase
 cargo capacity for truck trucks that are weight-limited.
 Wide-base tires have  lower rolling resistance and
 aerodynamic drag, and generateslightly less pass-by
 noise than do dual tires.

 The new generation of wide-base tires has a section
 width of up to  17.5 inches, so these tires comply with
 pavement weight laws  in all 50 states, for a typical
 tandem  axle  combination   truck.   For  some
 non-tandem axle combination trucks, wide-base tires
 may not  comply with  "inch-width" laws  in certain
 states.

 Wide-base tires  can improve the stability of tank
 trailers by allowing the tank to be mounted lower. In
 a test of 15 fleets driving 57 million miles using its
 latest wide-base tire  models,  one manufacturer
 reported that the  tires wear at a rate comparable to
 conventional  tires.  Wide-base  tires  also can  be
 retreaded.

 Several factors associated with wide-base tires have
 limited their use to date.  Some of the factors  result
 from fleets' unfamiliarity with this technology, and its
 lack of availability. Wide-base tires are not as yet
 widely stocked by repair facilities, so drivers  might
 not  easily find  replacements while on  the  road.
 Fleets may  need to alter retread methods, and
 monitor air pressure more closely. The shift in wheel
 bearing load position could stress and prematurely
 shorten the life of certain wheel ends. Since the tires
     are not paired, some drivers question whether they
     would be immobilized if a wide-base tire failed. Tire
     makers respond to this concern by noting that since
     most combination trucks have tandem axles, they
     could still operate if a wide-base  tire fails. The new
     generation of wide-base tires has a different aspect,
     and  initial U.S. tests indicate these tires cause no
     more damage to roads than standard tires do. Earlier
     versions increased road rutting and cracking, leading
     many  states to  discourage their  use.  The older
     version of wide-base tires is still  sold,  but intended
     only for specific applications (mining, construction,
     cement trucks and equipment).


     The  results  are in ...
     Recent tests of wide-base tires indicate a potential
     fuel  economy improvement of 2  to 5  percent
     compared  to equivalent  dual  tires.  By  using
     wide-base tires, a combination long-haul truck could
     save over  400 gallons of fuel  per year and  cut
     emissions of carbon dioxide  (the  most common
     greenhouse gas) by more  than four metric tons
     annually.  Most importantly,  these environmental
     benefits can often be achieved while cutting costs. A
     single  wide-base tire costs about the same  as two
     equivalent dual tires and a single wide-rim wheel
     typically costs about $130 less than two standard
     wheels.  Retrofitting existing trucks with  wide-base
     tires and wheels may not be cost effective. However,
     for new trucks, the "payback" is instantaneous, since
     the initial savings could exceed $1,000. In addition,
     fuel savings begin immediately.


     Next steps
     Fleet owners should consider purchasing tractors
     and  trailers with wide-based tires on their next new
     truck purchases.  Wide-base tire assemblies  are
     cheaper  than dual  tire assemblies  and  provide
     immediate   fuel   economy savings.  For  more
     information, talk  to your tire and truck dealers or
     contact  the  American  Trucking  Associations'
     Technology  and   Maintenance   Council
     (www.trucking.org).
S. Environmental Protection Agency • Office of Transportatli
February 2004. EPA420-F-04-004. • For more Information,.visit:www.epa.gov/smartway

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