2007 CADILLAC STS Owners Manual

Buying New Tires
GM has developed and matched specic tires for
your vehicle. The original equipment tires
installed on your vehicle, when it was new, were
designed to meet General Motors Tire
Performance Criteria Specication (TPC Spec)
system rating. If you need replacement tires, GM
strongly recommends that you get tires with
the same TPC Spec rating. This way, your vehicle
will continue to have tires that are designed to
give the same performance and vehicle safety,
during normal use, as the original tires.
GM’s exclusive TPC Spec system considers over
a dozen critical specications that impact the
overall performance of your vehicle, including
brake system performance, ride and handling,
traction control, and tire pressure monitoring
performance. GM’s TPC Spec number is moldedonto the tire’s sidewall by the tire manufacturer. If
the tires have an all-season tread design, the
TPC Spec number will be followed by an MS for
mud and snow. SeeTire Sidewall Labeling on
page 423for additional information.
The optional 18-inch performance tires, size
255/45ZR18 99Y, used on some vehicles, meet
the General Motors Tire Performance Criteria
Specication (TPC Spec) rating but the TPC Spec
code has not been molded onto the tire’s
sidewall. If your vehicle has these tires, and you
need to replace them, you can still get these TPC
Spec rated tires by asking your GM dealer.
Your GM dealer can order these tires by part
number. This way, your vehicle will continue to
give the proper endurance, handling, traction, and
ride as the original tires.
441

Winter tires with the same speed rating as your
original equipment tires may not be available for H,
V, W, Y and ZR speed rated tires. If you choose
snow tires with a lower speed rating, never exceed
the tire’s maximum speed capability.
{CAUTION:
Mixing tires could cause you to lose
control while driving. If you mix tires of
different sizes (other than those originally
installed on your vehicle), brands, or
types (radial and bias-belted tires), the
vehicle may not handle properly, and you
could have a crash. Using tires of
different sizes (other than those originally
installed on your vehicle), brands, or
types may also cause damage to your
vehicle. Be sure to use the correct size,
brand, and type of tires on all wheels. It is
all right to drive with your vehicle’s
compact spare temporarily, it was
developed for use on your vehicle. See
Compact Spare Tire on page 475.
{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.
If you must replace your vehicle’s tires with those
that do not have a TPC Spec number, make
sure they are the same size, load range, speed
rating, and construction type (radial and
bias-belted tires) as your vehicle’s original tires.
Vehicles that have a tire pressure monitoring
system may give an inaccurate low-pressure
warning if non-TPC Spec rated tires are installed
on it. Non-TPC Spec rated tires may give a
low-pressure warning that is higher or lower than
the proper warning level you would get with
TPC Spec rated tires. SeeTire Pressure Monitor
System on page 433.
442

Your vehicle’s original equipment tires are listed
on the Tire and Loading Information label.
This label is attached to the vehicle’s center pillar
(B-pillar). SeeLoading Your Vehicle on page 349,
for more information about the Tire and Loading
Information label and its location on your vehicle.
Vehicles that have performance tires
P235/50R17 95V (front axle) and P255/45R17 98V
(rear axle) are mounted on wheels with different
rim widths. The front axle tires are mounted
on rims 7.5 inches (19.05 cm) wide and the rear
axle tires require wheels with a minimum rim width
of 8 inches (20.32 cm). The original equipment
wheels designed for P255/45R17 98V size
tires are etched with the words REAR ONLY.
When replacing P255/45R17 98V size tires have
them mounted on wheels with a minimum width of
8 inches (20.32 cm) and marked REAR ONLY.
SeeWheel Replacement on page 445.
Different Size Tires and Wheels
If you add wheels or tires that are a different size
than your original equipment wheels and tires,
this may affect the way your vehicle performs,
including its braking, ride and handling
characteristics, stability, and resistance to rollover.Additionally, if your vehicle has electronic systems
such as, anti-lock brakes, traction control, and
electronic stability control, the performance
of these systems can be affected.
{CAUTION:
If you add different sized wheels, your
vehicle may not provide an acceptable
level of performance and safety if tires not
recommended for those wheels are
selected. You may increase the chance
that you will crash and suffer serious
injury. Only use GM specic wheel and
tire systems developed for your vehicle,
and have them properly installed by a GM
certied technician.
SeeBuying New Tires on page 441and
Accessories and Modications on page 363for
additional information.
443

Uniform Tire Quality Grading
Quality grades can be found where applicable on
the tire sidewall between tread shoulder and
maximum section width. For example:
Treadwear 200 Traction AA Temperature A
The following information relates to the system
developed by the United States National Highway
Traffic Safety Administration (NHTSA), which
grades tires by treadwear, traction, and
temperature performance. This applies only to
vehicles sold in the United States. The grades are
molded on the sidewalls of most passenger car
tires. The Uniform Tire Quality Grading (UTQG)
system does not apply to deep tread, winter-type
snow tires, space-saver, or temporary use
spare tires, tires with nominal rim diameters of
10 to 12 inches (25 to 30 cm), or to some
limited-production tires.
While the tires available on General Motors
passenger cars and light trucks may vary with
respect to these grades, they must also conform to
federal safety requirements and additional General
Motors Tire Performance Criteria (TPC) standards.
Treadwear
The treadwear grade is a comparative rating based
on the wear rate of the tire when tested under
controlled conditions on a specied government
test course. For example, a tire graded 150 would
wear one and a half (1.5) times as well on the
government course as a tire graded 100. The
relative performance of tires depends upon the
actual conditions of their use, however, and may
depart signicantly from the norm due to variations
in driving habits, service practices, and differences
in road characteristics and climate.
Traction – AA, A, B, C
The traction grades, from highest to lowest, are
AA, A, B, and C. Those grades represent the tire’s
ability to stop on wet pavement as measured under
controlled conditions on specied government test
surfaces of asphalt and concrete. A tire marked
C may have poor traction performance.
Warning:The traction grade assigned to this tire
is based on straight-ahead braking traction
tests, and does not include acceleration, cornering,
hydroplaning, or peak traction characteristics.
444

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
specied 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 inated
and not overloaded. Excessive speed,
underination, or excessive loading, either
separately or in combination, can cause heat
buildup and possible tire failure.
Wheel Alignment and Tire Balance
The tires and wheels on your vehicle were aligned
and balanced carefully at the factory to give you
the longest tire life and best overall performance.
Adjustments to wheel alignment and tire
balancing will not be necessary on a regular basis.
However, if you notice unusual tire wear or your
vehicle pulling to one side or the other, the
alignment may need to be checked. If you notice
your vehicle vibrating when driving on a smooth
road, your tires and wheels may need to be
rebalanced. See your dealer for proper diagnosis.
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.
445

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 or tire chain clearance
to the body and chassis.
SeeChanging a Flat Tire on page 464for more
information.
Used Replacement Wheels
{CAUTION:
Putting a used wheel on your vehicle is
dangerous. You cannot know how it has
been used or how far it has been driven. It
could fail suddenly and cause a crash. If
you have to replace a wheel, use a new
GM original equipment wheel.
446

Tire Chains
{CAUTION:
If your vehicle has P255/45R17,
P255/45R18, P275/40R19, or 255/45ZR18
size tires, do not use tire chains, as there
is not enough clearance.
Tire chains used on a vehicle without the
proper amount of clearance can cause
damage to the brakes, suspension, or
other vehicle parts. The area damaged by
the tire chains could cause you to lose
control of your vehicle and you or others
may be injured in a crash.
Use another type of traction device only if
its manufacturer recommends it for use
on your vehicle and tire size combination
and road conditions. Follow that
manufacturer’s instructions.
CAUTION: (Continued)
CAUTION: (Continued)
To help avoid damage to your vehicle,
drive slowly, readjust, or remove the
device if it is contacting your vehicle, and
do not spin your vehicle’s wheels.
If you do nd traction devices that will t,
install them on the rear tires only.
Notice:If your vehicle has P235/50R17 95S
size tires, use tire chains only where legal and
only when you must. Use only SAE Class
S-type chains that are the proper size for your
tires. Install them on the rear tires and
tighten them as tightly as possible with the
ends securely fastened. Drive slowly and follow
the chain manufacturer’s instructions. If you
can hear the chains contacting your vehicle,
stop and retighten them. If the contact
continues, slow down until it stops. Driving
too fast or spinning the wheels with chains on
will damage your vehicle.
447

Lifting Your Vehicle (STS-V)
{CAUTION:
Lifting a vehicle can cause an injury. The
vehicle can slip off the jack and roll over
you or other people. You and they could
be badly injured. Find a level place to lift
your vehicle. To help prevent the vehicle
from moving:
1. Hold the brake pedal down with your
right foot.
2. Move the shift lever in PARK (P) by
pressing the button on the front of
the shift lever while pushing the lever
all the way toward the front of the
vehicle. Release the button.
3. With your right foot still holding the
brake pedal down, set the parking
brake with your left foot.
4. Turn off the engine.
CAUTION: (Continued)
CAUTION: (Continued)
To be even more certain the vehicle will
not move, you can put blocks in front of
and behind the wheels. Also, seeShifting
Into Park (P) on page 122andParking
Brake on page 121for additional
information.
{CAUTION:
Getting under a vehicle when it is jacked
up is dangerous. If the vehicle slips off
the jack, you could be badly injured or
killed. Never get under a vehicle when it is
supported only by a jack.
448