Geo PRIZM 1993 Manual page 247

The tire has a bump, bulge or split.
The tire has a puncture, cut, or other
damage that can't be repaired well
because of the size or location of the
damage.
Buying New Tires
To find out what kind and size of tires
you need, look at the Tire-Loading
Information label.
Make sure the replacements are the
same size, load range, speed rating and
construction type (bias, bias-belted or
radial) as your original tires.
CA UTlON
I
A
Mixing tires could cause you
to lose control while driving.
If you mix tires of different sizes
or types (radial and bias-belted
tires), the vehicle may not handle
properly, and you could have a
crash. Be sure to
use
the same size
and type tires
on
all
wheels.
It's all right to drive with your
compact spare, though. It was
developed for limited use on your
vehicle.
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 150 would
wear one and a half (1 1/2) 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