Treadwear Temperature -- A, B, C
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 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 -- A, B, C
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 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. 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 l.oading, either separately or in combination,
can cause heat buildup and possible tire failure.
6-44
ProCarManuals.com
