Table of Contents
Advertisement
Tire Rotation (Rearward Cross)
DEPARTMENT OF TRANSPORTATION
UNIFORM TIRE QUALITY GRADES
The following tire grading categories
were established by the National High-
way 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
your vehicle.
All passenger vehicle tires must con-
form 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 con-
ditions 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 rela-
tive performance of tires depends
upon the actual conditions of their
use, however, and may depart signifi-
cantly 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 speci-
fied government test surfaces of
asphalt and concrete. A tire marked C
may have poor traction performance.
SERVICING AND MAINTENANCE
WARNING!
The traction grade assigned to this
tire is based on straight-ahead brak-
ing traction tests, and does not
include acceleration, cornering,
hydroplaning, or peak traction
characteristics.
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 condi-
tions 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 tem-
perature can lead to sudden tire fail-
ure. The grade C corresponds to a level
of performance, which all passenger
vehicle tires must meet under the Fed-
eral Motor Vehicle Safety Standard No.
297
8
Advertisement
Table of Contents
