Buick RIVIERA 1993 Manual page 250

Buying New .Tires
To find out what kind and size of tires you need, look at
:the Tire-Loading Information label.
The tires installed on your vehicle when it was new had
a Tire Performance Criteria Specification (TPC Spec)
number on each tire's sidewall. When you get new tires,
:get ones with that same TPC Spec number. That way,
*your vehicle will continue to have tires that are designed
to give proper endurance, handling, speed rating,
traction, ride and other things during normal service on
your vehicle. If your tires have an all-season tread
design, the TPC number will be followed by a "MS',
(for mud and snow).
;If
you ever replace your tires with those not having a
!.TPC Spec number, make sure they are the same size,
load rdnge, speed rating and construction type (bias,
bias-belted or radial) as your original tires.
,
A
CAUTION:
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
1
vehicle may not handle properly, and you cou'
'
have a crash. Be sure to use the same size ana
type tires on all four wheels.
It's all right to drive with your compact spa
though. It was developed for use on your
vehicle.
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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
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