wheel CADILLAC XLR 2004 1.G Service Manual

(A) P-Metric Tire:The United States version of a
metric tire sizing system. The letter ªPº as the
®rst character in the tire size means a passenger
vehicle tire engineered to standards set by the U. S.
Tire and Rim Association.
(B) Tire Width:The three-digit number indicates the
tire section width in millimeters from sidewall to sidewall.
(C) Aspect Ratio:A two-digit number that indicates
the tire height-to-width measurements. For example, if
the tire size aspect ratio is ª70,º as shown in item ªCº of
the illustration, it would mean that the tire's sidewall is
70% as high as it is wide.
(D) Construction Code:A letter code is used to
indicate the type of ply construction in the tire. The letter
ªRº means radial ply construction; the letter ªDº means
diagonal or bias ply construction; and the letter ªBº
means belted-bias ply construction.
(E) Rim Diameter:Diameter of the wheel in inches.
(F) Service Description:These characters represent
the load range and the speed rating of a tire. The
load range represents the load carrying capacity a tire is
certi®ed to carry. The load index can range from 1 to
279. The speed rating is the maximum speed a tire
is certi®ed to carry a load. Speed ratings range
from ªAº to ªZº.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 In¯ation Pressure:The amount of air pressure in
a tire, measured in pounds per square inch (psi)
before a tire has built up heat from driving. See
In¯ation - Tire Pressure on page 5-57.
5-53

Run-Flat Tires
Your vehicle, when new, had run-¯at tires. There's no
spare tire, no tire changing equipment and no place
to store a tire in the vehicle. Run-¯at tires perform so
well without any air that a Tire Pressure Monitor
(TPM) is used to alert you if a tire has lost pressure.
If a tire goes ¯at, you won't need to stop on the side of
the road to change the tire. You can just keep on
driving. The shorter the distance you drive and the
slower the speed, the greater the chance that the tire will
not have to be replaced. If you drive on a de¯ated
run- ¯at tire for 50 miles (80 km) or less and at speeds
of 55 mph (90 km/h) or less, there is a good chance
that the tire can be repaired. The tire can operate
effectively with no air pressure for up to 200 miles
(320 km) at speeds up to 55 mph (90 km/h), but the tire
would then have to be replaced. When a tire is ®lled
with air, it provides a cushion between the road and the
wheel. Because you won't have this cushion when
driving on a de¯ated tire, try to avoid potholes that could
damage your wheel and require replacement of it.Some road hazards can damage a tire beyond repair.
This damage could occur even before you've driven
on the tire in a de¯ated condition. When a tire has been
damaged, or if you've driven any distance on a
run-¯at tire, check with an authorized run-¯at tire service
center to determine whether the tire can be repaired
or should be replaced. To maintain your vehicle's run-¯at
feature, all replacement tires must be self-supporting
tires. As soon as possible, contact the nearest
authorized GM or run-¯at servicing facility for inspection
and repair or replacement. To locate the nearest GM
or run-¯at servicing facility, call Roadside Assistance.
For phone numbers and Roadside Service details
see
Roadside Service on page 7-5.
{CAUTION:
Run-¯at tires are constructed differently than
other tires and could explode during improper
service. You or others could be injured or
killed if you attempt to repair, replace,
dismount, or mount a run-¯at tire. Let only an
authorized run-¯at service center repair,
replace, dismount and mount run-¯at tires.
5-56

The valve stems on your run-¯at tires have sensors that
are part of the Tire Pressure Monitor System (TPMS).
See
Tire Pressure Monitor System on page 5-58. These
sensors contain batteries which are designed to last
for 10 years under normal driving conditions. See your
dealer if you ever need to have a wheel replaced,
or if the sensors ever need replacement.
Notice:Using liquid sealants can damage the tire
valves and tire pressure monitor sensors in your
run-¯at tires. This damage would not be covered
by warranty. Don't use liquid sealants in your
run-¯at tires.
In¯ation - Tire Pressure
The Tire and Loading Information label, shows the
correct in¯ation pressures for your tires when they're
cold. ªColdº means your vehicle has been sitting for at
least three hours or driven no more than 1 mile
(1.6 km). See
Loading Your Vehicle on page 4-32for more information on the Tire and Loading
Information label.
Notice:Don't let anyone tell you that underin¯ation
or overin¯ation is all right. It's not. If your tires
don't have enough air (underin¯ation), you can get
the following:
·Too much ¯exing
·Too much heat
·Tire overloading
·Bad wear
·Bad handling
·Bad fuel economy
If your tires have too much air (overin¯ation), you
can get the following:
·Unusual wear
·Bad handling
·Rough ride
·Needless damage from road hazards
5-57

When to Check
Check your tires once a month or more.
How to Check
Use a good quality pocket-type gage to check tire
pressure. You can't tell if your tires are properly in¯ated
simply by looking at them. Radial tires may look
properly in¯ated even when they're underin¯ated. Check
tire in¯ation pressure when the tire is 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. 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.
Tire Pressure Monitor (TPM)
Your vehicle has a Tire Pressure Monitor (TPM) that
sends tire pressure information to the Driver Information
Center (DIC). Using the DIC control buttons, the
driver is able to check tire pressure levels in all four
road tires. See
Tire Pressure Monitor System on
page 5-58andDIC Controls and Displays on page 3-55for additional information.
Tire Pressure Monitor System
The Tire Pressure Monitor (TPM) System on your
vehicle, uses radio and sensor technology to check tire
pressure levels. Sensors, mounted on each tire and
wheel assembly transmit tire pressure readings to
a receiver located in the vehicle. The TPM sensors
transmit tire pressure readings once every 60 seconds
while the vehicle is being driven and once every
60 minutes when the vehicle is stationary for more than
15 minutes. Using the Driver Information Center
(DIC), tire pressure levels can be viewed by the driver.
The TPM system also uses the DIC to warn the
driver when air pressure, in one or more tires, falls
below 25 psi (172 kPa) or is above 38 psi (262 kPa).
For additional information and details about the
DIC operation and displays see
DIC Controls and
Displays on page 3-55andDIC Warnings and Messages
on page 3-57.
5-58

A low tire warning light also appears on the instrument
panel cluster when a low tire condition exists. The
DIC message, CHECK TIRE PRESSURE and the low
tire pressure warning light will be shown each time
the engine is started and stay on until the low tire
condition is corrected.
When the tire pressure
monitoring system warning
light is lit, one or more
of your tires is signi®cantly
under-in¯ated.
You should stop and check your tires as soon as
possible, and in¯ate them to the proper pressure as
indicated on the vehicle's tire information placard.
Driving on a signi®cantly under-in¯ated tire causes the
tire to overheat and can lead to tire failure.
Under-in¯ation also reduces fuel efficiency and tire tread
life, and may affect the vehicle's handling and stopping
ability. Each tire, including the spare, should be
checked monthly when cold and set to the
recommended in¯ation pressure as speci®ed in the
vehicle placard and owner's manual.The Tire and Loading Information Label (tire information
placard) is either on the rear edge of the driver's door
or the driver's door jamb near the latch. This label shows
the size of your vehicle's original tires and the correct
in¯ation pressure for your vehicle's tires when they
are cold. See
In¯ation - Tire Pressure on page 5-57.
Your vehicle's TPM system can alert you about a low or
high tire pressure condition but it does not replace
normal tire maintenance. See
Tire Inspection and
Rotation on page 5-60
Each TPM sensor has a unique identi®cation code that
is matched to one of the four tire positions on your
vehicle. The tire and wheel assembly positions are, left
front (LF); right front (RF); right rear (RR) and left
rear (LR). Any time you rotate your vehicle's tires or
replace one or more TPM sensors, the identi®cation
codes will need to be matched to the new tire and wheel
position. The TPM matching process is performed in
a speci®c sequence and time limit. A special tool is also
required. See your dealer for service.
The SVC TIRE MONITOR message is displayed when
the TPM system is malfunctioning. For example,
one or more TPM sensors may be inoperable or
missing. See your dealer for service.
5-59

The TPM system operates on a radio frequency subject
to Federal Communications Commission (FCC) Rules
and with Industry and Science Canada.
This device complies with Part 15 of the FCC Rules and
with RSS-210 of Industry and Science Canada.
Operation is subject to the following two conditions:
(1) This device may not cause harmful interference, and
(2) this device must accept any interference received
including interference that may cause undesired
operation of the device.
Changes or modi®cations to this system by other than
an authorized service facility could void authorization to
use this equipment.Tire Inspection and Rotation
Your vehicle's tires should be inspected regularly for
wear. Any time you notice unusual wear, rotate
your tires as soon as possible and check wheel
alignment. Also check for damaged tires or wheels. See
When It Is Time for New Tires on page 5-62andWheel Replacement on page 5-66for additional
information.
When rotating your vehicle's tires, always use the
correct rotation pattern shown here.
5-60

After the tires have been rotated, adjust the front and
rear in¯ation pressures as shown on the tire and loading
information label, see
In¯ation - Tire Pressure on
page 5-57andLoading Your Vehicle on page 4-32.
Vehicles equipped with the Tire Pressure Monitor (TPM)
system will need to have the sensors reset after a tire
rotation is performed. A special tool is needed to
reset the sensor identi®cation codes. See your dealer
for service. Make certain that all wheel nuts are properly
tightened. See
Wheel Replacement on page 5-66and
ªWheel Nut Torqueº underCapacities and Speci®cations
on page 5-91.
{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 a crash. 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.
5-61

Buying New Tires
To ®nd out what kind and size of tires you need, look at
the Tire and Loading Information label. For information
about this label and where to ®nd it, see
Loading
Your Vehicle on page 4-32.
The tires installed on your vehicle when it was new had
a Tire Performance Criteria Speci®cation (TPC Spec)
number on each tire's sidewall. When you get new tires,
GM recommends that you get tires with that same
TPC Spec number. That way your vehicle will continue
to have tires that are designed to give proper
endurance, handling, speed rating, load range, traction,
ride, tire pressure monitoring system performance
and other things during normal service on your vehicle.
If your tires have an all-season tread design, the
TPC number will be followed by an ªMSº (for mud
and snow).
Whenever you replace your tires with those not having
a TPC Spec number, make sure they are the same
size, load range, speed rating and construction
type (bias, bias-belted or radial) as your original tires.
If you replace your vehicle's tires with those not having a
TPC Spec number, the tire pressure monitoring
system may give an inaccurate low-pressure warning.
Non-TPC Spec tires may give a low-pressure warning
that is higher or lower than the proper warning level you
would get with TPC Spec numbered 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.
{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.
5-63

Temperature ± A, B, C
The temperature grades are A (the highest), B, and C,
representing the tire's resistance to the generation
of heat and its ability to dissipate heat when tested
under controlled conditions on a speci®ed indoor
laboratory test wheel. Sustained high temperature can
cause the material of the tire to degenerate and
reduce tire life, and excessive temperature can lead to
sudden tire failure. The grade C corresponds to a
level of performance which all passenger car tires must
meet under the Federal Motor Vehicle Safety Standard
No. 109. Grades B and A represent higher levels of
performance on the laboratory test wheel than the
minimum required by law.
Warning: The temperature grade for this tire is
established for a tire that is properly in¯ated and not
overloaded. Excessive speed, underin¯ation, or
excessive loading, either separately or in combination,
can cause heat buildup and possible tire failure.
Wheel Alignment and Tire Balance
The wheels on your vehicle were aligned and balanced
carefully at the factory to give you the longest tire life
and best overall performance.
Scheduled wheel alignment and wheel balancing are
not needed. However, if you notice unusual tire wear or
your vehicle pulling one way or the other, the alignment
may need to be reset. If you notice your vehicle
vibrating when driving on a smooth road, your wheels
may need to be rebalanced.
5-65

Wheel Replacement
Replace any wheel that is bent, cracked, or badly rusted
or corroded. If wheel nuts keep coming loose, the
wheel, wheel bolts and wheel nuts should be replaced.
If the wheel leaks air, replace it (except some
aluminum wheels, which can sometimes be repaired).
See your dealer if any of these conditions exist.
Your dealer will know the kind of wheel you need.
Each new wheel should have the same load-carrying
capacity, diameter, width, offset and be mounted
the same way as the one it replaces.
If you need to replace any of your wheels, wheel bolts
or wheel nuts, replace them only with new GM
original equipment parts. This way, you will be sure to
have the right wheel, wheel bolts and wheel nuts
for your vehicle.{CAUTION:
Using the wrong replacement wheels, wheel
bolts or wheel nuts on your vehicle can be
dangerous. It could affect the braking and
handling of your vehicle, make your tires lose
air and make you lose control. You could have
a collision in which you or others could be
injured. Always use the correct wheel, wheel
bolts and wheel nuts for replacement.
Notice: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 clearance to the
body and chassis.
5-66