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426 SERVICING AND MAINTENANCE
All passenger vehicle tires must conform
to Federal safety requirements in
addition to these grades.
TREADWEAR
The Treadwear grade is a comparative
rating, based on the wear rate of the tire
when tested under controlled conditions
on a specified government test course.
For example, a tire graded 150 would
wear one and one-half times as well
on the government course as a tire
graded 100. The relative performance
of tires depends upon the actual
conditions of their use, however, and
may depart significantly from the norm
due to variations in driving habits,
service practices, and differences in
road characteristics and climate.
TRACTION GRADES
The Traction grades, from highest to
lowest, are AA, A, B, and C. These grades
represent the tire's ability to stop on
wet pavement, as measured under
controlled conditions on specified
government test surfaces of asphalt
and concrete. A tire marked C may
have poor traction performance.
TEMPERATURE GRADES
The Temperature grades are A (the
highest), B, and C, representing the tire's
resistance to the generation of heat and
its ability to dissipate heat, when tested
under controlled conditions on a
specified indoor laboratory test wheel.
Sustained high temperature can cause
the material of the tire to degenerate
and reduce tire life, and excessive
temperature can lead to sudden tire
failure. The grade C corresponds to a level
of performance, which all passenger
vehicle tires must meet under the Federal
Motor Vehicle Safety Standard No. 109.
Grades B and A represent higher levels of
performance on the laboratory test wheel,
than the minimum required by law.
WARNING!
The traction grade assigned to this tire is
based on straight-ahead braking traction
tests, and does not include acceleration,
cornering, hydroplaning, or peak traction
characteristics.
WARNING!
The temperature grade for this tire is
established for a tire that is properly inflated
and not overloaded. Excessive speed,
under-inflation, or excessive loading, either
separately or in combination, can cause heat
buildup and possible tire failure.
21_DPF_OM_EN_USC_t.book Page 426
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