Buick 1993 Century Owner's Manual page 257

*
I A
CAUTION:
Mlxing tires could cause you to lose control
while driving. If you mlx tires of different sizes
or types (radial and bias-belted tires) the
vehlcle may not handle properly, and you
could have
a
crash. Be sure to use the same
size and type tires on all four wheels. It's all
right to drive wlth your compact spare,
though. It was developed far use on your
vehicle.
I
Uniform Tire Quality Grading
The following information relates to the system developed
by the United States National Highway Traffic Safety
Administration which grades tires by treadwear, traction
and temperature performance. (This applies only to
vehicles sold in the United States.)
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 1 5 0 would wear one and a half
(1%) 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-A, B, C
The traction grades, from highest to lowest are: A, B,
and C. 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.
255