2008 CADILLAC DTS tires

Headlamp Aiming
The vehicle has a visual optical headlamp aiming
system. The aim has been preset at the factory and
should need no further adjustment.
However, if the vehicle is damaged in a crash, the
headlamp aim may be affected and adjustment may
be necessary.
If oncoming vehicles ash their high beams at you, this
may also mean the vertical aim needs to be adjusted.
It is recommended that the vehicle is taken to your
dealer/retailer for service if the headlamps need to
be re-aimed. It is possible however, to re-aim the
headlamps as described.
Notice:To make sure your headlamps are aimed
properly, read all the instructions before beginning.
Failure to follow these instructions could cause
damage to headlamp parts.The vehicle should:Be placed so the headlamps are 25 ft. (7.6 m) from
a light colored wall.
Have all four tires on a level surface which is level
all the way to the wall.
Be placed so it is perpendicular to the wall.
Not have any snow, ice, or mud on it.
Be fully assembled and all other work stopped while
headlamp aiming is being performed.
Be normally loaded with a full tank of fuel and one
person or 160 lbs (75 kg) sitting on the driver seat.
Have all tires properly inated.
Have the spare tire is in its original location in the
vehicle.
Headlamp aiming is done with the vehicle’s low-beam
headlamps. The high-beam headlamps will be correctly
aimed if the low-beam headlamps are aimed properly.
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Tires
Your new vehicle comes with high-quality tires
made by a leading tire manufacturer. If you ever
have questions about your tire warranty and where
to obtain service, see your vehicle Warranty
booklet for details.
{CAUTION:
Poorly maintained and improperly
used tires are dangerous.
Overloading your tires can cause
overheating as a result of too much
exing. You could have an air-out and
a serious accident. SeeLoading the
Vehicle on page 4-20.
CAUTION: (Continued)
CAUTION: (Continued)

Underinated tires pose the same
danger as overloaded tires. The
resulting accident could cause serious
injury. Check all tires frequently to
maintain the recommended pressure.
Tire pressure should be checked when
your tires are cold. SeeInflation - Tire
Pressure on page 5-60.
Overinated tires are more likely
to be cut, punctured, or broken by
a sudden impact — such as when
you hit a pothole. Keep tires at the
recommended pressure.
Worn, old tires can cause accidents. If
your tread is badly worn, or if your tires
have been damaged, replace them.
SeeHigh-Speed Operation on page 5-62for
ination pressure adjustment for high
speed driving.
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Tire Sidewall Labeling
Useful information about a tire is molded into its
sidewall.
(A) Tire Size
:The tire size is a combination of
letters and numbers used to dene 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
Specication)
:Original equipment tires designed
to GM’s specic tire performance criteria have
a TPC specication code molded onto the sidewall.
GM’s TPC specications 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 Identication Number (TIN)
:The letters
and numbers following the DOT code are the Tire
Identication 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 see
Uniform Tire Quality Grading on page 5-74.Passenger Car Tire Example
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(G) TPC Spec (Tire Performance Criteria
Specication):Original equipment tires designed
to GM’s specic tire performance criteria have a
TPC specication code molded onto the sidewall.
GM’s TPC specications meet or exceed all federal
safety guidelines.
(A) Tire Size
:The tire size code is a combination
of letters and numbers used to dene 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
Specication)
:Original equipment tires designed
to GM’s specic tire performance criteria have
a TPC specication code molded onto the sidewall.
GM’s TPC specications meet or exceed all
federal safety guidelines.
(C) Dual Tire Maximum Load
:Maximum load
that can be carried and the maximum pressure
needed to support that load when used in a dual
conguration.
(D) 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.
(E) Tire Identication Number (TIN)
:The letters
and numbers following DOT code are the Tire
Identication 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.
(F) Tire Ply Material
:The type of cord and
number of plies in the sidewall and under the tread.
Light Truck Tire Example
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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 5-70.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 5-74.
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 4-20.
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 4-20.
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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 Tire and Loading Information label is attached
to the vehicle’s center pillar. 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, see
Loading the Vehicle on page 4-20. How you load
your vehicle affects the 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 spare tire. If your vehicle has a
compact spare tire, it should be at 60 psi (420 kPa).
For additional information seeSpare Tire on
page 5-89.
5-60

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
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.
Professional Vehicle
The proper ination of the tires on your
professional vehicle depends on the type
of tires on it.
If your vehicle has P235/60R17 size tires, the
cold ination pressure is 41 psi (284 kPa).
If your vehicle has LT235/60R17E size tires,
the cold ination pressure depends on the
vehicle mass and should be determined by
the vehicle coach-builder. A Tire and Loading
Information label provided by the nal stage
manufacturer should be attached to the B-pillar
on the driver’s side of the vehicle. If the nal
stage manufacturer’s label is not present, the
coach-builder should be consulted. Do not use
the tire pressures indicated on the General
Motors label. These tire pressures are for the
incomplete vehicle and are not the correct tire
pressures for the completed professional
vehicle.
Operation at ination pressures below this
recommendation may cause your tires to become
overloaded.
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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 your vehicle has P235/55R17 or P245/50R18 size
tires, and you will be driving at 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.
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).
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 4-20.
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