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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.
(5) Tire Ply Material
:The
type of cord and number of
plies in the sidewall and
under the tread.
(6) Uniform Tire Quality
Grading (UTQG)
:Tire
manufacturers are required
to grade tires based on
three performance factors:
tread wear, traction, and
temperature resistance.
For more information see
Uniform Tire Quality
Grading 0385.
(7) Maximum Cold
Inflation Load Limit
:
Maximum load that can be
carried and the maximum
pressure needed to
support that load.
Compact Spare Tire Example
(1) Tire Ply Material:The
type of cord and number of
plies in the sidewall and
under the tread.
(2) Temporary Use Only
:
The compact spare tire or
temporary use tire should
not be driven at speeds
over 80 km/h (50 mph). The
compact spare tire is for
emergency use when a
regular road tire has lost
air and gone flat. If the
vehicle has a compact spare tire, see Compact
Spare Tire
0404 and
If a Tire Goes Flat 0389.
(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
Inflation Load Limit
:
Maximum load that can be
carried and the maximum
pressure needed to
support that load.
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(5) Tire Inflation: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 0372.
(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 example shows a
typical passenger vehicle
tire size.
Passenger (P-Metric) Tire
(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 3-digit
number indicates the tire
section width in millimeters
from sidewall to sidewall.
(3) Aspect Ratio
:A 2-digit
number that indicates the
tire height-to-width
measurements. For
example, if the tire size
aspect ratio is 75, as
shown in item (3) of the
illustration, it would mean
that the tire's sidewall is
75 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 diagonal or bias ply
construction.
(5) Rim Diameter
:
Diameter of the wheel in
inches.
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(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).
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 kPa
(kilopascal) or psi (pounds
per square inch) before a
tire has built up heat from
driving. See Tire Pressure
0 372. 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 0242.
GAWR FRT
:Gross Axle
Weight Rating for the front
axle. See Vehicle Load
Limits 0242.
GAWR RR
:Gross Axle
Weight Rating for the rear
axle. See Vehicle Load
Limits 0242.
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Intended Outboard
Sidewall
:The side of an
asymmetrical tire, that
must always face outward
when mounted on a vehicle.
Kilopascal (kPa)
:The
metric unit for air pressure.
Light Truck (LT-Metric)
Tire
:A tire used on light
duty trucks and some
multipurpose passenger
vehicles.
Load Index
:An assigned
number ranging from 1 to
279 that corresponds to
the load carrying capacity
of a tire.
Maximum Inflation
Pressure
:The maximum
air pressure to which a cold
tire can be inflated. The
maximum air pressure is
molded onto the sidewall. Maximum Load Rating
:
The load rating for a tire at
the maximum permissible
inflation pressure for
that tire.
Occupant Distribution
:
Designated seating
positions.
Outward Facing Sidewall
:
The side of an
asymmetrical tire that has
a particular side that faces
outward when mounted on
a vehicle. The side of the
tire that contains a
whitewall, bears white
lettering, or bears
manufacturer, brand, and/
or model name molding
that is higher or deeper
than the same moldings on
the other sidewall of
the tire.
Passenger (P-Metric)
Tire
:A tire used on
passenger cars and some
light duty trucks and
multipurpose vehicles.
Recommended Inflation
Pressure
:Vehicle
manufacturer's
recommended tire inflation
pressure as shown on the
tire placard. See Tire
Pressure 0372 and
Vehicle Load Limits 0242.
Radial Ply Tire
:A
pneumatic tire in which the
ply cords that extend to
the beads are laid at
90 degrees to the
centerline of the tread.
Rim
:A metal support for a
tire and upon which the tire
beads are seated.
Sidewall
:The portion of a
tire between the tread and
the bead.
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Speed Rating:An
alphanumeric code
assigned to a tire indicating
the maximum speed at
which a tire can operate.
Traction
:The friction
between the tire and the
road surface. The amount
of grip provided.
Tread
:The portion of a
tire that comes into
contact with the road.
Treadwear Indicators
:
Narrow bands, sometimes
called wear bars, that show
across the tread of a tire
when only 1.6 mm (1/16 in)
of tread remains. See
When It Is Time for New
Tires 0382.
UTQGS (Uniform Tire
Quality Grading
Standards)
:A tire
information system that
provides consumers with
ratings for a tire's traction, temperature, and
treadwear. Ratings are
determined by tire
manufacturers using
government testing
procedures. The ratings
are molded into the
sidewall of the tire. See
Uniform Tire Quality
Grading
0385.
Vehicle Capacity Weight
:
The number of designated
seating positions multiplied
by 68 kg (150 lbs) plus the
rated cargo load. See
Vehicle Load Limits 0242.
Vehicle Maximum Load on
the Tire
:Load on an
individual tire due to curb
weight, accessory weight,
occupant weight, and cargo
weight.
Vehicle Placard
:A label
permanently attached to a
vehicle showing the
vehicle's capacity weight and the original equipment
tire size and recommended
inflation pressure. See
“Tire
and Loading Information
Label” under Vehicle Load
Limits 0242.
Tire Pressure
Tires need the correct
amount of air pressure to
operate effectively.
{Warning
Neither tire underinflation
nor overinflation is good.
Underinflated tires,
or tires that do not have
enough air, can result in:
.Tire overloading and
overheating, which
could lead to a blowout
.Premature or
irregular wear
.Poor handling
(Continued)
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Warning (Continued)
.Reduced fuel economy
for internal combustion
engine vehicles
.Reduced range for
electric vehicles
Overinflated tires, or tires
that have too much air,
can result in:
.Unusual wear
.Poor handling
.Rough ride
.Needless damage from
road hazards
The Tire and Loading
Information label on the
vehicle indicates the
original equipment tires
and the correct cold tire
inflation pressures. The recommended pressure is
the minimum air pressure
needed to support the
vehicle's maximum load
carrying capacity. See
Vehicle Load Limits
0242.
How the vehicle is loaded
affects vehicle handling
and ride comfort. Never
load the vehicle with more
weight than it was
designed to carry.
When to Check
Check the pressure of the
tires once a month or more.
Do not forget the spare,
if the vehicle has one. The
compact spare cold tire
pressure should be at
420 kPa (60 psi). See
Compact Spare Tire 0404. How to Check
Use a good quality
pocket-type gauge to
check tire pressure. Proper
tire inflation cannot be
determined by looking at
the tire. Check the tire
inflation pressure when the
tires are cold, meaning the
vehicle has not been driven
for at least three hours or
no more than 1.6 km (1 mi).
Remove the valve cap from
the tire valve stem. Press
the tire gauge firmly onto
the valve to get a pressure
measurement. If the cold
tire inflation pressure
matches the recommended
pressure on the Tire and
Loading Information label,
no further adjustment is
necessary. If the inflation
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pressure is low, add air
until the recommended
pressure is reached. If the
inflation pressure is high,
press on the metal stem in
the center of the tire valve
to release air.
Recheck the tire pressure
with the tire gauge.
Put the valve caps back on
the valve stems to keep out
dirt and moisture. Use only
valve caps designed for the
vehicle by GM. TPMS
sensors could be damaged
and would not be covered
by the vehicle warranty.
Tire Pressure for
High-Speed Operation
{Warning
Driving at high speeds,
160 km/h (100 mph) or
higher, puts additional strain(Continued)
Warning (Continued)
on tires. Sustained
high-speed driving causes
excessive heat buildup and
can cause sudden tire
failure. This could cause a
crash, and you or others
could be killed. Some
high-speed rated tires
require inflation pressure
adjustment for high-speed
operation. When speed
limits and road conditions
allow the vehicle to be
driven at high speeds, make
sure the tires are rated for
high-speed operation, are in
excellent condition, and are
set to the correct cold tire
inflation pressure for the
vehicle load. Vehicles with tire sizes listed
in the High Speed Operation
Inflation Pressures table
require inflation pressure
adjustment when driving the
vehicle at speeds of 160 km/h
(100 mph) or higher. Set the
cold tire inflation pressure to
the corresponding value in the
table for the tire size on the
vehicle.
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High Speed Operation Inflation Pressures
Tire Size Cold Inflation Pressure kPa (psi)
235/55R18 260 kPa (38 psi)
245/45R20 260 kPa (38 psi)
Return the tires to the
recommended cold tire
inflation pressure when
high-speed driving has ended.
See Vehicle Load Limits 0242
and Tire Pressure 0372.
Tire Pressure Monitor
System
The Tire Pressure Monitor
System (TPMS) uses radio and
sensor technology to check
tire pressure levels. The TPMS
sensors monitor the air
pressure in your tires and
transmit tire pressure
readings to a receiver located
in the vehicle.
Each tire, including the spare
(if provided), should be
checked monthly when cold and inflated to the inflation
pressure recommended by the
vehicle manufacturer on the
vehicle placard or tire inflation
pressure label. (If your vehicle
has tires of a different size
than the size indicated on the
vehicle placard or tire inflation
pressure label, you should
determine the proper tire
inflation pressure for those
tires.)
As an added safety feature,
your vehicle has been
equipped with a tire pressure
monitoring system (TPMS)
that illuminates a low tire
pressure telltale when one or
more of your tires is
significantly under-inflated.
Accordingly, when the low tire
pressure telltale illuminates,
you should stop and check
your tires as soon as possible,
and inflate them to the proper
pressure. Driving on a
significantly under-inflated tire
causes the tire to overheat
and can lead to tire failure.
Under-inflation also reduces
energy efficiency and tire
tread life, and may affect the
vehicle's handling and
stopping ability.
Please note that the TPMS is
not a substitute for proper tire
maintenance, and it is the
driver's responsibility to
maintain correct tire pressure,
even if under-inflation has not