2009 CADILLAC STS Owners Manual

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 Tire 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. SeeInflation - Tire Pressure on
page 5-64.
Curb Weight
: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.
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GVWR:Gross Vehicle Weight Rating.
SeeLoading the Vehicle on page 4-24.
GAWR FRT
:Gross Axle Weight Rating for the
front axle. SeeLoading the Vehicle on page 4-24.
GAWR RR
:Gross Axle Weight Rating for the
rear axle. SeeLoading the Vehicle on page 4-24.
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 Ination Pressure
:The maximum
air pressure to which a cold tire can 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 the Vehicle on
page 4-24.
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.
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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
as shown on the tire placard. SeeInflation - Tire
Pressure on page 5-64andLoading the Vehicle
on page 4-24.
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.
SeeWhen It Is Time for New Tires on page 5-73.
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 on page 5-77.
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 4-24.
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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 the
Vehicle on page 4-24.
Run-Flat Tires (STS-V)
If your vehicle has run-at tires, there is no spare tire
and no tire changing equipment. Your vehicle also has a
Tire Pressure Monitor System (TPMS) which will alert
you if there is a loss of tire pressure in any of the tires.
SeeTire Pressure Monitor System on page 5-66.
{CAUTION:
When the low tire warning light is displayed
on the instrument panel cluster, your vehicle’s
handling capabilities will be reduced during severe
maneuvers. If you drive too fast, you could lose
control of your vehicle. You or others could be
injured. Do not drive over 55 mph (90 km/h)
when the low tire warning light is displayed.
Drive cautiously and check your tire pressures
as soon as you can.
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If a tire goes at, you will not need to stop on the side of
the road to change the tire. You can just keep on driving.
The vehicle’s run-at tires can operate effectively with no
air pressure for up to 50 miles (80 km) at speeds up to
55 mph (90 km/h). The shorter the distance you drive and
the slower the speed, the greater the chance that the tire
will not have to be replaced. When a tire is lled with air,
it provides a cushion between the road and the wheel.
Because you will not have this cushion when driving on
a deated run-at 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 have driven
on the tire in a deated condition. When a tire has been
damaged, or if you have driven any distance on a
deated run-at tire, check with an authorized run-at
tire service center, as soon as possible, 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.
To locate the nearest GM or authorized run-at
servicing facility, call Roadside Service. See
Roadside Service on page 7-7for details.
{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.
The valve stems on your vehicle’s run-at tires have
sensors that are part of the Tire Pressure Monitor
System (TPMS). These sensors contain batteries which
are designed to last for 10 years under normal driving
conditions. See your GM dealer, if the TPMS sensors or
a wheel ever need replacement.
Notice:Using liquid sealants can damage the tire
valves and tire pressure monitor sensors in the
vehicle’s run-at tires. This damage would not be
covered by warranty. Do not use liquid sealants
in the vehicle’s run-at tires.
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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 hazardsA vehicle specic Tire and Loading Information
label is attached to your vehicle. 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
the Vehicle on page 4-24. 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, if your
vehicle has one. The compact spare should be
at 60 psi (420 kPa). For additional information
regarding the compact spare tire, seeCompact
Spare Tire on page 5-114.
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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 are
underinated. 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.
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.
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When you end this high-speed driving, return the tires
to the cold ination pressure shown on the Tire and
Loading Information label. SeeLoading the Vehicle
on page 4-24.
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 System (TPMS) uses radio
and sensor technology to check tire pressure levels.
The TPMS sensors monitor the air pressure in your
vehicle’s 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 inated to the ination
pressure recommended by the vehicle manufacturer
on the vehicle placard or tire ination pressure label.
(If your vehicle has tires of a different size than the
size indicated on the vehicle placard or tire ination
pressure label, you should determine the proper
tire ination 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 signicantly under-inated.
Accordingly, when the low tire pressure telltale
illuminates, you should stop and check your tires as
soon as possible, and inate them to the proper pressure.
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.
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