FORD 2001 Focus - Manual (Page 221)

Maintenance and care
221
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.
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.