Tire Terminology and Definitions
Air Pressure:The amount of air inside the tire
pressing outward on each square inch of the tire.
Air pressure is expressed in pounds per square
inch (psi) or kilopascal (kPa).
Accessory Weight:This means the combined
weight of optional accessories. Some examples of
optional accessories are, automatic transmission,
power steering, power brakes, power windows,
power seats, and air conditioning.
Aspect Ratio:The relationship of a tire's height
to its width.
Belt:A rubber coated layer of cords that is
located between the plies and the tread. Cords
may be made from steel or other reinforcing
materials.
Bead:The tire bead contains steel wires wrapped
by steel cords that hold the tire onto the rim.
Bias Ply Tire:A pneumatic tire in which the plies
are laid at alternate angles less than 90 degrees
to the centerline of the tread.
Cold Tire Pressure:The amount of air pressure
in a tire, measured in pounds per square inch (psi)
or kilopascals (kPa) before a tire has built up heat
from driving. SeeInflation - Tire Pressureon
page 7!65.
Curb Weight:The weight of a motor vehicle with
standard and optional equipment including the
maximum capacity of fuel, oil, and coolant, but
without passengers and cargo.
DOT Markings:A code molded into the sidewall
of a tire signifying that the tire is in compliance
with the U.S. Department of Transportation (DOT)
motor vehicle safety standards. The DOT code
includes the Tire Identification Number (TIN), an
alphanumeric designator which can also identify
the tire manufacturer, production plant, brand, and
date of production.
GVWR:Gross Vehicle Weight Rating. See
Loading the Vehicleon page 6!32.
GAWR FRT:Gross Axle Weight Rating for the
front axle. SeeLoading the Vehicleon page 6!32.
GAWR RR:Gross Axle Weight Rating for the rear
axle. SeeLoading the Vehicleon page 6!32.
7-62
If you need to replace any of your wheels, wheel bolts,wheel nuts, or Tire Pressure Monitor System (TPMS)sensors, replace them only with new GM originalequipment parts. This way, you will be sure to havethe right wheel, wheel bolts, wheel nuts, and TPMSsensors for your vehicle.
{WARNING:
Using the wrong replacement wheels, wheel bolts,
or wheel nuts on your vehicle can be dangerous.
It could affect the braking and handling of your
vehicle, make your tires lose air and make you
lose control. You could have a collision in which
you or others could be injured. Always use the
correct wheel, wheel bolts, and wheel nuts for
replacement.
Notice:The wrong wheel can also cause problemswith bearing life, brake cooling, speedometer orodometer calibration, headlamp aim, bumper height,vehicle ground clearance, and tire or tire chainclearance to the body and chassis.
SeeChanging a Flat Tireon page 7!80for moreinformation.
Used Replacement Wheels
{WARNING:
Putting a used wheel on the vehicle is dangerous.
You cannot know how it has been used or how
far it has been driven. It could fail suddenly and
cause a crash. If you have to replace a wheel,
use a new GM original equipment wheel.
Tire Chains
{WARNING:
Do not use tire chains. There is not enough
clearance. Tire chains used on a vehicle without
the proper amount of clearance can cause
damage to the brakes, suspension, or other
vehicle parts. The area damaged by the tire
chains could cause you to lose control of the
vehicle and you or others may be injured in a
crash. Use another type of traction device only if
its manufacturer recommends it for use on the
(Continued)
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