
Loss of Control
Let us review what driving experts say about what
happens when the three control systems — brakes,
steering, and acceleration — do not have enough friction
where the tires meet the road to do what the driver
has asked.
In any emergency, do not give up. Keep trying to steer
and constantly seek an escape route or area of less
danger.
Skidding
In a skid, a driver can lose control of the vehicle.
Defensive drivers avoid most skids by taking reasonable
care suited to existing conditions, and by not overdriving
those conditions. But skids are always possible.
The three types of skids correspond to the vehicle’s three
control systems. In the braking skid, the wheels are not
rolling. In the steering or cornering skid, too much speed
or steering in a curve causes tires to slip and lose
cornering force. And in the acceleration skid, too much
throttle causes the driving wheels to spin.
Remember: StabiliTrak
®assists the driver with
directional control. SeeStabiliTrak®System on
page 5-6. If the StabiliTrak®System is off, then a
steering or cornering skid will need to be handledentirely by the driver using counter steering techniques
and an acceleration skid will be best handled by
easing your foot off the accelerator pedal.
If the vehicle starts to slide, ease your foot off the
accelerator pedal and quickly steer the way you want
the vehicle to go. If you start steering quickly enough,
the vehicle may straighten out. Always be ready for
a second skid if it occurs.
Of course, traction is reduced when water, snow, ice,
gravel, or other material is on the road. For safety, slow
down and adjust your driving to these conditions. It is
important to slow down on slippery surfaces because
stopping distance will be longer and vehicle control more
limited.
While driving on a surface with reduced traction, try your
best to avoid sudden steering, acceleration, or braking,
including reducing vehicle speed by shifting to a lower
gear. Any sudden changes could cause the tires to
slide. You may not realize the surface is slippery until
the vehicle is skidding. Learn to recognize warning
clues — such as enough water, ice, or packed snow on
the road to make a mirrored surface — and slow down
when you have any doubt.
Remember: Any Antilock Brake System (ABS) helps
avoid only the braking skid.
5-12

Driving in Rain and on Wet Roads
Rain and wet roads can reduce vehicle traction
and affect your ability to stop and accelerate. Always
drive slower in these types of driving conditions
and avoid driving through large puddles and
deep-standing or flowing water.
{WARNING:
Wet brakes can cause crashes. They might not
work as well in a quick stop and could cause
pulling to one side. You could lose control of the
vehicle.
After driving through a large puddle of water or a
car/vehicle wash, lightly apply the brake pedal until
the brakes work normally.
Flowing or rushing water creates strong forces.
Driving through flowing water could cause your
vehicle to be carried away. If this happens, you
and other vehicle occupants could drown. Do not
ignore police warnings and be very cautious about
trying to drive through flowing water.
Hydroplaning
Hydroplaning is dangerous. Water can build up under
your vehicle’s tires so they actually ride on the
water. This can happen if the road is wet enough and
you are going fast enough. When your vehicle is
hydroplaning, it has little or no contact with the road.
There is no hard and fast rule about hydroplaning. The
best advice is to slow down when the road is wet.
Other Rainy Weather Tips
Besides slowing down, other wet weather driving tips
include:
•Allow extra following distance.
•Pass with caution.
•Keep windshield wiping equipment in good shape.
•Keep the windshield washer fluid reservoir filled.
•Have good tires with proper tread depth. SeeTires
on page 6-57.
•Turn off cruise control.
5-26

Tire Sidewall Labeling
Useful information about a tire is molded into its
sidewall. The examples below show a typical
passenger vehicle tire and a compact spare tire
sidewall.(A) Tire Size
:The tire size is a combination of
letters and numbers used to define 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
Speci cation)
:Original equipment tires designed
to GM’s specific tire performance criteria have a
TPC specification code molded onto the sidewall.
GM’s TPC specifications 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 Identi cation Number (TIN)
:The letters
and numbers following DOT code are the Tire
Identification 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.
Passenger Vehicle Tire Example
6-58

(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 seeUniform Tire Quality Grading on
page 6-75.
(G) Maximum Cold In ation Load Limit
:Maximum load that can be carried and the
maximum pressure needed to support that load.(A) Temporary Use Only
:The compact
spare tire or temporary use tire has a tread life of
approximately 3,000 miles (5 000 km) and should
not be driven at speeds over 65 mph (105 km/h).
The compact spare tire is for emergency use
when a regular road tire has lost air and gone flat.
See “Compact Spare Tire” underSpare Tire on
page 6-101for additional information.
(B) Tire Ply Material
:The type of cord and
number of plies in the sidewall and under
the tread.
(C) Tire Identi cation Number (TIN)
:The Tire
Identification 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.
(D) Maximum Cold In ation Load Limit
:Maximum load that can be carried and the
maximum pressure needed to support that load.
(E) Tire In ation
:The temporary use tire or
compact spare tire should be inflated to 60 psi
(420 kPa). For more information on tire pressure
and inflation seeIn ation - Tire Pressure on
page 6-64.
Compact Spare Tire Example
6-59

(F) Tire Size:A combination of letters and
numbers define a tire’s width, height, aspect
ratio, construction type and service description.
The letter T as the first character in the tire
size means the tire is for temporary use only.
(G) TPC Spec (Tire Performance Criteria
Speci cation)
:Original equipment tires designed
to GM’s specific tire performance criteria have a
TPC specification code molded onto the sidewall.
GM’s TPC specifications meet or exceed all federal
safety guidelines.
Tire Size
The following illustration shows an example of a
typical passenger vehicle tire size.
(A) P-Metric Tire
:The United States version of
a metric tire sizing system. The letter P as the first
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 70, as
shown in item C of the illustration, it would mean
that the tire’s sidewall is 70 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 index and speed rating of the
tire. The load index represents the load carry
capacity a tire is certified to carry. The speed
rating is the maximum speed a tire is certified
to carry a load.
6-60

How to Check
Use a good quality pocket-type gage to check tire
pressure. You cannot tell if your tires are properly
inflated simply by looking at them. Radial tires
may look properly inflated even when they are
underinflated. Check the tire’s inflation 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 firmly onto the valve to
get a pressure measurement. If the cold tire
inflation pressure matches the recommended
pressure on the Tire and Loading Information
label, no further adjustment is necessary. If the
inflation pressure is low, add air until you reach
the recommended amount.
If you overfill 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.
High-Speed Operation
{WARNING:
Driving at high speeds, 160 km/h (100 mph) 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 inflation 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 inflation
pressure for the vehicle load.
If your vehicle has P235/50R18 size tires, they will
require inflation pressure adjustment when driving your
vehicle at speeds of 100 mph (160 km/h) or higher.
6-65

GM recommends replacing tires in sets of four. This is
because uniform tread depth on all tires will help keep
your vehicle performing most like it did when the tires
were new. Replacing less than a full set of tires can affect
the braking and handling performance of your vehicle.
SeeTire Inspection and Rotation on page 6-71for
information on proper tire rotation.
{WARNING:
Mixing tires could cause you to lose control of
your vehicle while driving. If you mix tires of
different sizes, 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, 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.
Your vehicle may have a compact spare tire and
wheel assembly. It is all right to drive with your
vehicle’s compact spare tire temporarily. It was
developed for use on your vehicle. SeeSpare Tire
on page 6-101.
{WARNING:
If you use bias-ply tires on the vehicle,
the wheel rim flanges 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
the 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
could give an inaccurate low-pressure warning if
non-TPC Spec rated tires are installed on your vehicle.
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 6-66.
Your vehicle’s original equipment tires are listed on
the Tire and Loading Information Label. SeeLoading the
Vehicle on page 5-33, for more information about the
Tire and Loading Information Label and its location
on your vehicle.
6-74

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, antilock brakes, traction control, and
electronic stability control, the performance of these
systems can be affected.
{WARNING:
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
specific wheel and tire systems developed for your
vehicle, and have them properly installed by a GM
certified technician.
SeeBuying New Tires on page 6-73andAccessories
and Modi cations on page 6-3for additional information.
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.
6-75