Uniform Tire Quality Grading Standards 555
form to Federal Safety Requirements
in addition to these grades.
& TREADWEAR
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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 (1-
1/2) 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 AA, A, B, C
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The traction grades, from highest to
lowest, are AA, A, B and C. Those
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.
WARNING
The traction grade assigned to
this tire is based on straightahead
braking traction tests,
and does not include acceleration,
cornering, hydroplaning,
or peak traction characteristics.
& TEMPERATURE A, B, C
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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
car 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 temperature grade for this
tire is established for a tire that
is properly inflated and not
overloaded. Excessive speed,
underinflation, or excessive
loading, either separately or
in combination, can cause
heat buildup and possible tire
failure.
Consumer Information and Reporting Safety Defects
13