Chevrolet 2011 Impala, Owner'S Manual

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Black plate (62,1)
Chevrolet Impala Owner Manual - 2011
10-62 Vehicle Care
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 a
half (1½) 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 – AA, A, B, C
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 performance.
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 – A, B, C
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 Safety
Standard No. 109. Grades B
and A represent higher
levels of performance on the
laboratory test wheel than
the minimum required by law.