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Summer Tires
This vehicle may come with high
performance summer tires. These tires
have a special tread and compound
that are optimized for maximum dry
and wet road performance. This
special tread and compound will have
decreased performance in cold
climates, and on ice and snow. It is
recommended that winter tires be
installed on the vehicle if frequent
driving at temperatures below
approximately 5 °C (40 °F) or on ice or
snow covered roads is expected. See
Winter Tires0268.
Caution
High performance summer tires
have rubber compounds that lose
flexibility and may develop surface
cracks in the tread area at
temperatures below −7 °C (20 °F).
Always store high performance
summer tires indoors and at
temperatures above −7 °C (20 °F)
when not in use. If the tires have
(Continued)
Caution (Continued)
been subjected to−7 °C (20 °F) or
less, let them warm up in a heated
space to at least 5 °C (40 °F) for
24 hours or more before being
installed or driving a vehicle on
which they are installed. Do not
apply heat or blow heated air
directly on the tires. Always inspect
tires before use. See Tire Inspection
0 280.
Tire Sidewall Labeling
Useful information about a tire is
molded into its sidewall. The
examples show a typical passenger
vehicle tire and a compact spare
tire sidewall.
Passenger (P-Metric) Tire Example
(1) Tire Size:The tire size is a
combination of letters and
numbers used to define a
particular tire's width, height,
aspect ratio, construction type,
and service description. See the
“Tire Size ”illustration later in this
section.
(2) TPC Spec (Tire Performance
Criteria Specification)
:Original
equipment tires designed to GM's
specific tire performance criteria
have a TPC specification code
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(3) Tire Identification Number
(TIN)
:The letters and numbers
following the DOT (Department of
Transportation) code are the Tire
Identification Number (TIN). The
TIN shows the manufacturer and
plant code, tire size, and date the
tire was manufactured. The TIN is
molded onto both sides of the tire,
although only one side may have
the date of manufacture.
(4) Maximum Cold Inf lation
Load Limit
:Maximum load that
can be carried and the maximum
pressure needed to support
that load.
(5) Tire Inf lation
:The temporary
use tire or compact spare tire
should be inflated to 420 kPa
(60 psi). For more information on
tire pressure and inflation see Tire
Pressure 0274.
(6) Tire Size
:A combination of
letters and numbers define a tire's
width, height, aspect ratio,
construction type, and service description. The letter T as the
first character in the tire size
means the tire is for temporary
use only.
(7) TPC Spec (Tire Performance
Criteria Specification)
:Original
equipment tires designed to GM's
specific tire performance criteria
have a TPC specification code
molded onto the sidewall. GM's
TPC specifications meet or exceed
all federal safety guidelines.
Tire Designations
Tire Size
The following is an example of a
typical passenger vehicle tire size.
(1) Passenger (P-Metric) Tire:
The United States version of a
metric tire sizing system. The
letter P as the first character in
the tire size means a passenger
vehicle tire engineered to
standards set by the U.S. Tire and
Rim Association.
(2) Tire Width
:The three-digit
number indicates the tire section
width in millimeters from sidewall
to sidewall.
(3) Aspect Ratio
:A two-digit
number that indicates the tire
height-to-width measurements.
For example, if the tire size aspect
ratio is 60, as shown in item 3 of
the illustration, it would mean
that the tire's sidewall is
60 percent as high as it is wide.
(4) 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
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272 VEHICLE CARE
diagonal or bias ply construction;
and the letter B means belted-bias
ply construction.
(5) Rim Diameter
:Diameter of
the wheel in inches.
(6) Service Description
:These
characters represent the load
index and speed rating of the tire.
The load index represents the load
carrying capacity a tire is certified
to carry. The speed rating is the
maximum speed a tire is certified
to carry a load.
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 kPa
(kilopascal) or psi (pounds per
square inch).
Accessory Weight
:The combined
weight of optional accessories.
Some examples of optional accessories are automatic
transmission, 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 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 kPa (kilopascal) or psi (pounds
per square inch) before a tire has
built up heat from driving. See
Tire Pressure 0274. 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 Vehicle Load Limits
0 176.
GAWR FRT
:Gross Axle Weight
Rating for the front axle. See
Vehicle Load Limits 0176.
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{Warning
Using the wrong replacement
wheels, wheel bolts, or wheel nuts
can be dangerous. It could affect
the braking and handling of the
vehicle. Tires can lose air, and
cause loss of control, causing a
crash. Always use the correct wheel,
wheel bolts, and wheel nuts for
replacement.
Caution
The wrong wheel can also cause
problems with bearing life, brake
cooling, speedometer or odometer
calibration, headlamp aim, bumper
height, vehicle ground clearance,
and tire or tire chain clearance to
the body and chassis.
Professional vehicle wheels have a
unique offset and bolt hole diameter.
Professional vehicle wheels have six wheel nuts. Non-professional vehicle
wheels have five wheel nuts. See
Tire
Changing 0295.
Used Replacement Wheels
{Warning
Replacing a wheel with a used one
is dangerous. How it has been used
or how far it has been driven may
be unknown. It could fail suddenly
and cause a crash. When replacing
wheels, 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,
(Continued)
Warning (Continued)
or other vehicle parts. The area
damaged by the tire chains could
cause loss of control and a crash.
Use another type of traction device
only if its manufacturer
recommends it for the vehicle's tire
size combination and road
conditions. Follow that
manufacturer's instructions. To
avoid vehicle damage, drive slow
and readjust or remove the traction
device if it contacts the vehicle. Do
not spin the wheels. If traction
devices are used, install them on
the front tires.
If a Tire Goes Flat
It is unusual for a tire to blow out
while driving, especially if the tires are
maintained properly. See Tires0267.
If air goes out of a tire, it is much
more likely to leak out slowly. But if
there is ever a blowout, here are a few
tips about what to expect and what
to do:
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