Tire Sidewall Labeling
Useful information about a tire is
molded into its sidewall. The
examples below show a typical
passenger vehicle tire and a
compact spare tire sidewall.
(A) Tire Size
:The tire size is a
combination of letters and
numbers used to de ne a
particular tire’s width, height,
aspect ratio, construction
type, and service description.See the “Tire Size” illustration
later in this section for more
detail.
(B) TPC Spec (Tire
Performance Criteria
Speci cation)
:Original
equipment tires designed to
GM’s speci c tire performance
criteria have a TPC speci cation
code molded onto the sidewall.
GM’s TPC speci cations meet
or exceed all federal safety
guidelines.
(C) DOT (Department
of Transportation)
:The
Department of Transportation
(DOT) code indicates that the
tire is in compliance with the U.S.
Department of Transportation
Motor Vehicle Safety Standards.
(D) Tire Identi cation Number
(TIN)
:The letters and numbers
following DOT (Department
of Transportation) code is the
Tire Identi cation 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.
(E) Tire Ply Material
:The type
of cord and number of plies in the
sidewall and under the tread.
(F) Uniform Tire Quality
Grading (UTQG)
:Tire
manufacturers are required to
grade tires based on three
performance factors: treadwear,
traction, and temperature
resistance. For more information
seeUniform Tire Quality
Grading on page 5-60.
(G) Maximum Cold In ation
Load Limit
:Maximum load that
can be carried and the maximum
pressure needed to support
that load. Passenger (P-Metric) Tire
Example
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(A) Temporary Use Only:The
compact spare tire or temporary
use tire has a tread life of
approximately 3,000 miles
(5 000 km) and should not be
driven at speeds over 65 mph
(105 km/h). The compact spare
tire is for emergency use when a
regular road tire has lost air and
gone at. If your vehicle has a
compact spare tire, seeCompact
Spare Tire on page 5-71andIf a
Tire Goes Flat on page 5-63.(B) Tire Ply Material
:The type
of cord and number of plies in the
sidewall and under the tread.
(C) Tire Identi cation Number
(TIN)
:The letters and numbers
following the DOT (Department
of Transportation) code is the
Tire Identi cation 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.
(D) Maximum Cold In ation
Load Limit
:Maximum load that
can be carried and the maximum
pressure needed to support
that load.
(E) Tire In ation
:The
temporary use tire or compact
spare tire should be in ated
to 60 psi (420 kPa). For more
information on tire pressure and
in ation seeInflation - Tire
Pressure on page 5-49.(F) Tire Size
:A combination of
letters and numbers de ne a
tire’s width, height, aspect ratio,
construction type, and service
description. The letter T as the
rst character in the tire size
means the tire is for temporary
use only.
(G) TPC Spec (Tire
Performance Criteria
Speci cation)
:Original
equipment tires designed to
GM’s speci c tire performance
criteria have a TPC speci cation
code molded onto the sidewall.
GM’s TPC speci cations meet
or exceed all federal safety
guidelines. Compact Spare Tire Example
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Maximum Loaded Vehicle
Weight:The sum of curb
weight, accessory weight,
vehicle capacity weight, and
production options weight.
Normal Occupant Weight
:The
number of occupants a vehicle
is designed to seat multiplied by
150 lbs (68 kg). SeeLoading
the Vehicle on page 4-28.
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 In ation
Pressure
:Vehicle
manufacturer’s recommended
tire in ation pressure as
shown on the tire placard. See
Inflation - Tire Pressure on
page 5-49andLoading
the Vehicle on page 4-28.
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.
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 1/16 inch
(1.6 mm) of tread remains. See
When It Is Time for New Tires on
page 5-57.
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. SeeUniform Tire Quality
Grading on page 5-60.
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Vehicle Capacity Weight:The
number of designated seating
positions multiplied by 150 lbs
(68 kg) plus the rated cargo load.
SeeLoading the Vehicle on
page 4-28.
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 in ation pressure.
See “Tire and Loading
Information Label” under
Loading the Vehicle on
page 4-28.
In ation - Tire Pressure
Tires need the correct amount
of air pressure to operate
effectively.
Notice:Do not let anyone tell
you that under-in ation or
over-in ation is all right. It is
not. If your tires do not have
enough air (under-in ation),
you can get the following:
Too much exing
Too much heat
Tire overloading
Premature or irregular wear
Poor handling
Reduced fuel economy
If your tires have too much air
(over-in ation), you can get
the following:
Unusual wear
Poor handling
Rough ride
Needless damage from road
hazardsA vehicle speci c Tire and
Loading Information label is
attached to your vehicle. This
label shows your vehicle’s
original equipment tires and the
correct in ation pressures for
your tires when they are cold.
The recommended cold tire
in ation pressure, shown on the
label, is the minimum amount of
air pressure needed to support
your vehicle’s maximum load
carrying capacity.
For additional information
regarding how much weight
your vehicle can carry, and an
example of the Tire and Loading
Information label, seeLoading
the Vehicle on page 4-28. How
you load your vehicle affects
vehicle handling and ride
comfort. Never load your vehicle
with more weight than it was
designed to carry.
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When to Check
Check your tires once a month
or more. Do not forget to check
the compact spare tire, it should
be at 60 psi (420 kPa). For
additional information regarding
the compact spare tire, see
Compact Spare Tire on
page 5-71.
How to Check
Use a good quality pocket-type
gage to check tire pressure.
You cannot tell if your tires
are properly in ated simply by
looking at them. Radial tires may
look properly in ated even when
they are under-in ated. Check
the tire’s in ation pressure when
the tires are cold. Cold means
your vehicle has been sitting for
at least three hours or driven no
more than 1 mile (1.6 km).Remove the valve cap from the
tire valve stem. Press the tire
gage rmly onto the valve to
get a pressure measurement.
If the cold tire in ation pressure
matches the recommended
pressure on the Tire and Loading
Information label, no further
adjustment is necessary. If the
in ation pressure is low, add air
until you reach the recommended
amount.
If you over ll the tire, release air
by pushing on the metal stem
in the center of the tire valve.
Re-check the tire pressure with
the tire gage.
Be sure to put the valve caps
back on the valve stems.
They help prevent leaks by
keeping out dirt and moisture.High-Speed Operation
{CAUTION
Driving at high speeds, 100 mph
(160 km/h) or higher, puts an
additional strain on tires. Sustained
high-speed driving causes
excessive heat build up and can
cause sudden tire failure. You
could have a crash and you or
others could be killed. Some
high-speed rated tires require
in ation pressure adjustment for
high speed operation. When speed
limits and road conditions are such
that a vehicle can be driven at high
speeds, make sure the tires are
rated for high speed operation, in
excellent condition, and set to the
correct cold tire in ation pressure
for the vehicle load.
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