Open as PDF
DEPARTMENT OF TRANSPORTATION UNIFORM
TIRE QUALITY GRADES
The following describes the tire grading categories estab-
lished by the National highway Traffic Safety Adminis-
tration. The specific grade rating assigned by the tire’s
manufacturer in each category is shown on the sidewall
of the tires on your car.
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 con-
ditions on a specified government test course. For ex-
ample, a tire graded 150 would wear one and a 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.
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 perfor-
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.
IF YOU NEED CONSUMER ASSISTANCE 343