2005 CADILLAC STS Owners Manual

Tire Size
The following illustration shows an example of a typical
passenger vehicle tire size.
(A) Passenger (P-Metric) Tire:The United States
version of a metric tire sizing system. The letter P 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 60, as shown in item C of
the illustration, it would mean that the tire’s sidewall is
60 percent 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 R means radial ply construction; the letter D
means diagonal or bias ply construction; and the
letter B means belted-bias ply construction.
(E) Rim Diameter:Diameter of the wheel in inches.
(F) Service Description:These characters represent
the load range and speed rating of the tire. The load
index represents the load carry capacity a tire is certied
to carry. The load index can range from 1 to 279. The
speed rating is the maximum speed a tire is certied
to carry a load. Speed ratings range from A to Z.
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Tire Terminology and Denitions
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 Ination Pressure:The amount of air pressure in
a tire, measured in pounds per square inch (psi) or
kilopascals (kPa) before a tire has built up heat
from driving. SeeInation - Tire Pressure on page 5-60.Curb Weight:This means 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
Identication Number (TIN), an alphanumeric designator
which can also identify the tire manufacturer, production
plant, brand and date of production.
GVWR:Gross Vehicle Weight Rating, seeLoading
Your Vehicle on page 4-30.
GAWR FRT:Gross Axle Weight Rating for the front
axle, seeLoading Your Vehicle on page 4-30.
GAWR RR:Gross Axle Weight Rating for the rear axle,
seeLoading Your Vehicle on page 4-30.
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.
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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 air
pressure to which a cold tire may be inated. The
maximum air pressure is molded onto the sidewall.
Maximum Load Rating:The load rating for a tire at the
maximum permissible ination 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 lbs (68 kg).
SeeLoading Your Vehicle on page 4-30.
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 Ination Pressure:Vehicle
manufacturer’s recommended tire ination pressure and
shown on the tire placard. SeeInation - Tire Pressure
on page 5-60andLoading 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 1/16 inch (1.6 mm) of tread remains. See
When It Is Time for New Tires on page 5-67.
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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 5-70.
Vehicle Capacity Weight:The number of designated
seating positions multiplied by 150 lbs (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 the vehicle’s capacity weight and
the original equipment tire size and recommended
ination pressure. See “Tire and Loading Information
Label” underLoading 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
under-ination or over-ination is all right. It is not.
If your tires do not have enough air (under-ination),
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-ination), you
can get the following:
Unusual wear
Poor handling
Rough ride
Needless damage from road hazards
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A Tire and Loading Information label is attached to the
vehicle’s center pillar, below the driver’s door latch.
This label lists your vehicle’s original equipment
tires and shows the correct ination pressures for your
tires when they are cold. The recommended cold
tire ination 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 Your Vehicle
on page 4-30. How you load your vehicle affects
vehicle handling and ride comfort, never load your
vehicle with more weight than it was designed to carry.
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, seeCompact Spare Tire on
page 5-84.
How to Check
Use a good quality pocket-type gage to check tire
pressure. You cannot tell if your tires are properly inated
simply by looking at them. Radial tires may look properly
inated even when they’re under-inated. Check the tire’s
ination 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 ination pressure matches
the recommended pressure on the Tire and Loading
Information label, no further adjustment is necessary. If
the ination pressure is low, add air until you reach
the recommended amount.
If you overll 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.
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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.
If you will be driving at high speeds, speeds of 100 mph
(160 km/h) or higher, where it is legal, set the cold
ination pressure to the maximum ination pressure
shown on the tire sidewall, or 38 psi (265 kPa), whichever
is lower. See the example following. When you end this
high-speed driving, return the tires to the cold ination
pressure shown on the Tire and Loading Information
label. SeeLoading Your Vehicle on page 4-30.Example:
You will nd the maximum load and ination pressure
molded on the tire’s sidewall, in small letters, near
the rim ange. It will read something like this: Maximum
load 690 kg (1521 lbs) 300 kPa (44 psi) Max. Press.
For this example, you would set the ination pressure for
high-speed driving at 38 psi (265 kPa).
Tire Pressure Monitor System
The Tire Pressure Monitor (TPM) system uses radio and
sensor technology to check tire pressure levels. If your
vehicle has this feature, sensors are mounted on each
tire and wheel assembly, except for the compact spare
tire and wheel. Tire pressure readings are sent to a
receiver located in the vehicle once every 60 seconds
while the vehicle is being driven, and once every
60 minutes if the vehicle is stationary for more than
15 minutes.
Using the Driver Information Center (DIC), tire pressure
levels may be viewed by the driver. For additional
information and details about the DIC operation and
displays seeDIC Controls and Displays on page 3-74
andDIC Warnings and Messages on page 3-78.
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If a low tire pressure condition is detected, the TPM
system will display the CHECK TIRE PRESSURE
warning message on the Driver Information Center (DIC)
and, at the same time, illuminate the low tire pressure
warning symbol, on the instrument panel cluster.
When the tire pressure
monitoring system warning
light is lit, one or more
of your tires is signicantly
under-inated.
You should stop and check your tires as soon as
possible, and inate them to the proper pressure as
indicated on the vehicle’s tire information placard.
Driving on a signicantly under-inated tire causes the
tire to overheat and can lead to tire failure.
Under-ination 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 ination pressure as specied in the
vehicle placard and owner’s manual.The Tire and Loading Information Label (your vehicle’s
tire information placard) shows the size of your vehicle’s
original tires and the recommended cold ination
pressure for your vehicle’s tire. SeeInation - Tire
Pressure on page 5-60. For the location of the tire and
loading information label, seeLoading Your Vehicle on
page 4-30.
Your vehicle’s TPM system can alert you about a low
tire pressure condition but it does not replace normal tire
maintenance. SeeTire Inspection and Rotation on
page 5-65andTires on page 5-53.
Notice:Do not use a tire sealant if your vehicle is
equipped with Tire Pressure Monitors. The liquid
sealant can damage the tire pressure monitor
sensors.
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TPM Sensor Identication Codes
Each TPM sensor has a unique identication code. Any
time you replace one or more of the TPM sensors or
rotate your vehicle’s tires, the identication codes
will need to be matched to the new tire/wheel position.
The sensors are matched, to the tire/wheel positions,
in the following order: left front (LF), right front (RF), right
rear (RR), and left rear (LR) using a TPM diagnostic
tool. See your GM dealer for service.
The TPM sensors may also be matched to each
tire/wheel position by increasing or decreasing the tire’s
air pressure. If using this method to match TPM
sensors, the complete procedure outlined below must
be performed after the vehicle has been driven at
least 20 mph (32 km/h), for at least 10 seconds, and
within 15 minutes from when the vehicle is stationary.
You will have one minute to match the rst tire/wheel
position, and ve minutes overall, to match all four
tire/wheel positions. If it takes longer than one minute,
to match the rst tire and wheel, or more than ve
minutes to match all four tire/wheel positions the
matching process stops and you will need to start over.
The TPM matching process is outlined below:
1. Set the parking brake.
2. Press the push-button ignition switch to OFF/ACC.
3. Using the Keyless Access transmitter, lock and
unlock the vehicle’s doors.4. Press the lock and unlock buttons, at the same
time, on the Keyless Access transmitter. A single
horn chirp will sound, indicating that the TPM
system is ready, and the sensor matching process
can begin.
5. Start with the left (driver’s side) front tire.
6. Remove the valve cap from the valve stem.
Activate the TPM sensor by increasing or
decreasing the tire’s air pressure for ve seconds,
or until a horn chirp sounds. The horn chirp,
which may take up to 30 seconds, conrms that the
sensor identication code has been matched to
this tire position. To decrease the tire’s air-pressure
use the pointed end of the valve cap, a pencil-style
air pressure gauge, or a key.
7. Proceed to the right (passenger’s side) front tire,
and repeat the procedure in Step 6.
8. Proceed to the right (passenger’s side) rear tire,
and repeat the procedure in Step 6.
9. Proceed to the left (driver’s side) rear tire, and
repeat the procedure in Step 6.
10. After hearing the conrming double horn chirp, for
the left rear tire, exit the matching process by
pressing the push-button ignition switch to
OFF/ACC.
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