FORD 2002 Mustang v.1 - Manual (Page 242)

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 (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 AA A B C
The traction grades, from highest to lowest are AA,
A, B, and C. The 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.
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 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.
Maintenance and Specifications
242