GMC 1998 Savana Van Owner's Manual page 288

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.
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.
Wheel Alignment and Tire Balance
The wheels on your vehicle were aligned and balanced
carefully at the factory to give you the longest tire life
and best overall performance.
Scheduled wheel alignment and wheel balancing are
not needed. However, if you notice unusual tire wear
or your vehicle pulling one way or the other, the
alignment may need to be reset. If you notice your
vehicle vibrating when driving on a smooth road,
your wheels may need to be rebalanced.
6-48