Service manual
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
(1
112)
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
-
A,
B,
C
The traction grades, from highest to lowest are:
A,
B,
and
C.
They
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 braking
(straight-ahead) traction tests and does not include cornering (turning)
traction.
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 Vehicle
Safety Standard
No.
109.
Grades
B
and
A
represent higher levels of
performance on the laboratory test wheel than the minimum required by
law.
Warning:
The
temperature grade for this tire
is
established
for
a tire that
is properly inflated and not overloaded. Excessive speed, underinflation,
or excessive loading, either separately or in combination, can cause heat
buildup and possible tire failure.
Those grades are molded on the sidewalls
of
passenger car tires.
311