Jeep 2009 Grand Cherokee, Owner'S Manual

Page: 497 / 521

Treadwear
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.
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 specified government test surfaces of asphalt and
concrete. A tire marked C may have poor traction perfor-
mance.
WARNING!
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.
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 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
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