Chrysler 2004 Concorde - Manual (Page 259)

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.
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 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.
Traction Grades
The traction grades, from highest to lowest, are A, B, and
C, and they represent the tire’s ability to stop on wet
pavement as measured under controlled conditions on
specified government test surfaces of asphalt and con-
crete. A tire marked C may have poor traction perfor-
mance.
WARNING!
The traction grade is based on braking (straight-
ahead) traction tests and does not include cornering
(turning) performance.
Temperature Grades
The temperature grades are A (highest), B, and C, repre-
senting 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
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