(D) Construction Code:A letter code is used
to indicate the type of ply construction in the tire.
The letter R means radial ply construction; the
letter D means diagonal or bias ply construction;
and the letter B means belted-bias ply construction.
(E) Rim Diameter
:Diameter of the wheel in
inches.
(F) Service Description
:The service description
indicates the load range and speed rating of a
tire. The load index can range from 1 to 279.
Speed ratings range from A to Z.
Tire Terminology and De nitions
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 Pressure
on page 5-52.
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 Identi cation Number (TIN),
an alphanumeric designator which can also identify
the tire manufacturer, production plant, brand,
and date of production.
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Tire Pressure Monitor Operation
The Tire Pressure Monitor System (TPMS) is designed
to warn the driver when a low tire pressure condition
exists. TPMS sensors are mounted onto each tire and
wheel assembly. The TPMS sensors monitor the
air pressure in the vehicle’s tires and transmits the tire
pressure readings to a receiver located in the vehicle.
When a low tire pressure
condition is detected, the
TPMS turns on the low
tire pressure warning light
located on the instrument
panel cluster.
At the same time a message to check the pressure in a
speci c tire appears on the Driver Information Center
(DIC) display. The low tire pressure warning light
and the DIC warning message come on at each ignition
cycle until the tires are in ated to the correct in ation
pressure. Using the DIC, tire pressure levels can
be viewed by the driver.For additional information and details about the DIC
operation and displays seeDIC Operation and Displays
on page 3-44andDIC Warnings and Messages on
page 3-46.
The low tire pressure warning light may come on in
cool weather when the vehicle is rst started, and then
turn off as you start to drive. This could be an early
indicator that the air pressure in the tire(s) are getting
low and need to be in ated to the proper pressure.
A Tire and Loading Information label shows the size of
your vehicle’s original equipment tires and the correct
in ation pressure for your vehicle’s tires when they are
cold. SeeLoading Your Vehicle on page 4-22, for an
example of the Tire and Loading Information label and
its location on your vehicle. Also seeInflation - Tire
Pressure on page 5-52.
Your vehicle’s TPMS system can warn you about a low
tire pressure condition but it does not replace normal
tire maintenance. SeeTire Inspection and Rotation
on page 5-58andTires on page 5-46.
Notice:Using non-approved tire sealants could
damage the Tire Pressure Monitor System (TPMS)
sensors. TPMS sensor damage caused by using
an incorrect tire sealant is not covered by the
vehicle warranty. Always use the GM approved tire
sealant available through your dealer/retailer.
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