Pontiac 1996 Grand Am Owner's Manual page 264

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'(straightahead) 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 af performance
which all passenger
car
tires must meet under the
Federal Motor Vehicle Safety Standard No. 109. Grades
€3
and A represent higher levels of performance
on
the
laboratory test wheel than the minimum required by law.
Warning: The temperature gade 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 osn your vehicle were aligned
and balanced
carefully at the factory to give you the lo'ngest tire life
and best overall performance.
In
most cases, you..will not need to have your wheels
aligned again. 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.