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DEPARTMENT OF TRANSPORTATION UNIFORM
TIRE QUALITY GRADES
The following tire grading categories were established by
the National Highway Traffic Safety Administration. The
specific grade rating assigned by the tire’s manufacturer
in each category is shown on the sidewall of the tires on
All passenger car tires must conform to Federal safety
requirements in addition to these grades.
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 charac-
teristics and climate.
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.
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