Green Transport Partnership
                   A  Glance at Clean  Freight  Strategies:
                   Wide-Base  Tires
If wide-base
tires and
wheels are
installed on a
new truck, the
initial cost
saving alone is
more than
$1,000.  Fuel
savings  of at
least 2.7
What is  the challenge?
Rolling resistance accounts for approximately one-third of truck energy consumption.
Most combination trucks employ a dual tire assembly on the drive and trailer axles,
with two sets of wheels and tires at each end of an axle. This configuration results in
higher rolling resistance and increased truck weight, and hence lowers fuel economy.
What is  the solution?

A variety of tire options can improve truck fuel efficiency. The most promising strategy
is to use single wide-base tires instead of dual tires. A single wide-base tire and wide
wheel is lighter than two standard tires and wheels. Total weight savings amount to
nearly 1,000 pounds for a tractor-trailer, resulting either in reduced fuel consumption
(if the vehicle is volume-limited) or
increased cargo capacity (by reducing the
truck tare weight). Wide-base tires
also offer lower rolling resistance and
lower aerodynamic drag.

Single wide-base tires can be used
on the truck's drive and trailer axles.
The widest tires have a section width
of up to 17.5 inches, so they fully
comply with pavement weight laws in all 50
states for a standard combination truck configured with tandem axles. For some
combination trucks using non-tandem axles (such as single trailer axles), wide-base
tires will not comply with these "inch-width" laws in some states.

According to a recent paper by the Society of Automotive Engineers (SAE), wide-base
tires can be as safe as standard dual tires in the event  of a blowout. The tires can be
retreaded just like standard tires, and tests  by fifteen fleets driving over 57 million
miles found wide-base tires to wear at a comparable rate. Wide-base tires also
generate slightly less pass-by noise than standard dual tires.

Wide-base tires have several drawbacks that have limited their market penetration to
date. They are not widely stocked by truck maintenance and repair facilities, so
drivers may have trouble finding replacement tires in the event of a blowout on the
road. Because they are not mounted in pairs like standard tires, some drivers are also
concerned that failure of a wide-base tire will leave them immobilized. Tire
manufacturers dispute this claim, noting that because most tractors and trailers have
tandem axles, they can continue to operate with the failure of one wide-base tire.
                 Office of Transportation and Air Quality  Mailcode?  October 2002  EPA 420-F-02-018

  The  results  are in.
Recent tests of wide-base tires show a fuel economy improvement of 2.7 to 4.9
percent compared to equivalent dual tires. By using wide-base tires, a typical long-
haul truck can save at least 420 gallons of fuel per year and cut emissions of carbon
dioxide (the most common greenhouse gas) by more than four metric tonnes 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 costs less than two standard wheels. Retrofitting existing
trucks with wide-base tires and wheels is probably not cost effective. But because
components for the single tire assembly are approximately  $1,000 cheaper than a
standard dual tire assembly for new trucks, there is no payback time for this
investment in fuel economy. Gains are realized immediately.
Next steps
Fleet owners should consider purchasing tractors and trailers with wide-based tires on
their next truck purchases. Wide-base tires are cheaper than dual tires and provide
immediate fuel economy savings. For more information, talk to your tire and truck dealers
or contact the American Trucking Association's Technology and Maintenance Council.

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