Honda 1990 Accord Sedan Owner's Manual page 127

DOT Tire Quality Grades (cont'd)
Temperature
The temperature grades are A (the highest), B, and C represen-
ting the tire's resistance to the generation of heat and its abili-
ty 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 per-
formance 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 tire temperature grade 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.