tires PONTIAC GTO 2004 Owner's Manual

(A) 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 for more detail.
(B) Department of Transportation (DOT):The
Department of Transportation (DOT) code indicates that
the tire is in compliance with the U.S. Department of
Transportation Motor Vehicle Safety Standards.
(C) Tire Identication Number (TIN):The letters and
numbers following DOT 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.(D) Tire Ply Material:The type of cord and number of
plies in the sidewall and under the tread.
(E) 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 see
Uniform Tire Quality Grading on page 5-66.
(F) Maximum Cold Ination Load Limit:Maximum
load that can be carried and the maximum pressure
needed to support that load. For information on
recommended tire pressure seeInflation - Tire Pressure
on page 5-58andLoading Your Vehicle on page 4-30.
5-53

Load Index:An assigned number ranging
from 1 to 279 that corresponds to the load carrying
capacity of a tire.
Maximum Ination Pressure:The maximum cold
inflation pressure to which a tire may be inflated.
Maximum Load Rating:The load rating for a tire at
the maximum permissible inflation pressure for that tire.
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 pounds
(68 kg). SeeLoading Your Vehicle on page 4-30.
Occupant Distribution:Designated seating positions.
Outward Facing Sidewall:The side of a 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 Ination Pressure:Vehicle
manufacturer’s recommended tire inflation pressure
shown on the tire placard. SeeInflation - Tire Pressure
on page 5-58andLoading Your Vehicle on page 4-30.
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 2/32 inch of tread remains. SeeWhen It
Is Time for New Tires on page 5-64.
Tread Width:The width of the tire’s tread.
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 5-66.
Vehicle Capacity Weight:The number of designated
seating positions multiplied by 150 pounds (68 kg)
plus the rated cargo load. SeeLoading Your Vehicle on
page 4-30.
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 original equipment tire size and
the recommended cold inflation pressure. SeeLoading
Your Vehicle on page 4-30.Ination - Tire Pressure
Tires need the correct amount of air pressure to operate
effectively.
Notice:Do not let anyone tell you that
underination or overination is all right. It is not. If
your tires do not have enough air (underination),
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 (overination), you
can get the following:
Unusual wear
Poor handling
Rough ride
Needless damage from road hazards
5-58

A Tire and Loading Information label is attached to your
vehicle’s center pillar, below the driver’s door latch.
This label lists your vehicle’s original equipment
tires and their recommended cold tire inflation pressures.
The recommended cold tire inflation pressure, shown
on the label, is the minimum amount of air pressure
needed to support your vehicle’s maximum load carrying
capacity. For more information regarding how much
weight your vehicle can carry, seeLoading Your Vehicle
on page 4-30.How you load your vehicle affects vehicle handling and
ride comfort. When driving with less than the maximum
load capacity allowed for your vehicle, you can set
tire inflation pressure to the recommended amounts
shown in the following chart. Never load your vehicle
with more weight than it was designed to carry.
Tire SizeRecommended Cold Tire Ination
Occupant and Cargo
Weight: 470 lbs. (210 kg) or LessOccupant and Cargo
Weight: Up to 740 lbs. (330 kg)
(Vehicle Capacity Weight)
Front Tires Rear Tires Front Tires Rear Tires
245/45ZR17 95W 30 psi (210 kPa) 30 psi (210 kPa) 35 psi (240 kPa) 35 psi (240 kPa)
235/40ZR18 91W 33 psi (230 kPa) 33 psi (230 kPa) 33 psi (230 kPa) 39 psi (270 kPa)
T145/70R17 96M
(Compact Spare)60 psi (420 kPa) 60 psi (420 kPa) 60 psi (420 kPa) 60 psi (420 kPa)
5-59

When to Check
Check your tires once a month or more.
Do not forget your compact spare tire. It should be at
60 psi (420 kPa). For more information about your
vehicle’s compact spare tire, seeCompact Spare Tire
on page 5-77.
How to Check
Use a good quality pocket-type gage to check tire
pressure. You can’t tell if your tires are properly inflated
simply by looking at them. Radial tires may look
properly inflated even when they’re underinflated. Check
the tire’s inflation 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 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 pressure is low, add air until you reach
the recommended amount.
If you overfill the tire, release air by pushing on the
metal stem in the center of the tire valve. Recheck 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.
5-60

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 ination 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
ination pressure for the vehicle load.Vehicles equipped with 245/45ZR17 95W size tires, do
not require additional air pressure for high-speed
operation. If your vehicle has 235/40ZR18 91W size
tires, use the following chart to determine the cold tire
inflation pressure when operating your vehicle under
high-speed conditions.
Tire Size: 235/40ZR18 91W Recommended Cold
Tire Ination Pressure for High Speed Operation
Occupant and
Cargo Weight:
470 lbs. (210 kg) or lessOccupant and
Cargo Weight:
Up to 740 lbs. (330 kg)
(Vehicle Capacity
Weight)
Front
TiresRear Tires Front Tires Rear Tires
36 psi
(250 kPa)36 psi
(250 kPa)39 psi
(270 kPa)44 psi
(300 kPa)
When you end high-speed driving, return the tires to the
cold inflation pressure shown on the tire and loading
information label.
5-61

Tire Inspection and Rotation
Tires should be rotated every 5,000 to 8,000 miles
(8 000 to 13 000 km).
Any time you notice unusual wear, rotate your tires as
soon as possible and check wheel alignment. Also
check for damaged tires or wheels. SeeWhen It Is Time
for New Tires on page 5-64andWheel Replacement
on page 5-68for more information.
The purpose of regular rotation is to achieve more
uniform wear for all tires on the vehicle. The first rotation
is the most important. SeeScheduled Maintenance
on page 6-4.When rotating non-directional tires, always use the
correct rotation pattern shown here.
5-62

If your vehicle has 235/40ZR18 tires, they must roll in a
certain direction for the best overall performance.
The direction is shown by an arrow on the tire sidewall.
Because these tires are uni-directional, they should
be rotated as shown here. These tires should only be
moved from front to rear and rear to front on the
same side of the vehicle.
Don’t include the compact spare tire in your tire rotation.After the tires have been rotated, adjust the front and
rear inflation pressures as shown on the Tire and
Loading Information label. Make certain that all wheel
nuts are properly tightened. See “Wheel Nut Torque”
underCapacities and Specifications on page 5-92.
{CAUTION:
Rust or dirt on a wheel, or on the parts to
which it is fastened, can make wheel nuts
become loose after a time. The wheel could
come off and cause an accident. When you
change a wheel, remove any rust or dirt from
places where the wheel attaches to the vehicle.
In an emergency, you can use a cloth or a
paper towel to do this; but be sure to use a
scraper or wire brush later, if you need to, to
get all the rust or dirt off. See “Changing a Flat
Tire” in the Index.
5-63

When It Is Time for New Tires
One way to tell when it’s
time for new tires is to
check the treadwear
indicators, which will
appear when your tires
have only 1/16 inch
(1.6 mm) or less of tread
remaining.You need a new tire if any of the following statements
are true:•You can see the indicators at three or more places
around the tire.
•You can see cord or fabric showing through the
tire’s rubber.
•The tread or sidewall is cracked, cut or snagged
deep enough to show cord or fabric.
•The tire has a bump, bulge or split.
•The tire has a puncture, cut or other damage that
can’t be repaired well because of the size or
location of the damage.
5-64

Buying New Tires
To find out what kind and size of tires you need, look at
the Tire and Loading Information label. For more
information about this label and where to find it, see
Loading Your Vehicle on page 4-30.
Make sure the replacements are the same size,
load capacity, speed rating and construction type
(bias, bias-belted or radial) as your original tires.
{CAUTION:
Mixing tires could cause you to lose control
while driving. If you mix tires of different sizes
or types (radial and bias-belted tires), the
vehicle may not handle properly, and you
could have a crash. Using tires of different
sizes may also cause damage to your vehicle.
Be sure to use the same size and type tires on
all wheels. It’s all right to drive with your
compact spare temporarily, it was developed
for use on your vehicle. See “Compact Spare
Tire” in the index.
{CAUTION:
If you use bias-ply tires on your vehicle, the
wheel rim anges could develop cracks after
many miles of driving. A tire and/or wheel
could fail suddenly, causing a crash. Use only
radial-ply tires with the wheels on your vehicle.
5-65