Remember that your passenger side outside mirror
is convex. The vehicle you just passed may seem to
be farther away from you than it really is.
Try not to pass more than one vehicle at a time
on two-lane roads. Reconsider before passing the
next vehicle.
Do not overtake a slowly moving vehicle too rapidly.
Even though the brake lamps are not ashing,
it may be slowing down or starting to turn.
If you are being passed, make it easy for the
following driver to get ahead of you. Perhaps you
can ease a little to the right.
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 your vehicle’s
three control systems. In the braking skid, your 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.
A cornering skid is best handled by easing your foot off
the accelerator pedal.
If you have the Traction Control System (TCS),
remember: It helps avoid only the acceleration skid.
SeeTraction Control System (TCS) on page 4-9.Ifyou
do not have this system, or if the system is off, then
an acceleration skid is also best handled by easing
your foot off the accelerator pedal.
If your 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,
your vehicle may straighten out. Always be ready
for a second skid if it occurs.
4-15
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 de ne 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 speci c tire performance criteria have a TPC
speci cation code molded onto the sidewall. GM’s TPC
speci cations 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 (Department of Transportation)
code is the Tire Identi cation 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
seeUniform Tire Quality Grading on page 5-58.
(G) Maximum Cold In ation Load Limit:Maximum
load that can be carried and the maximum pressure
needed to support that load. Passenger (P-Metric) Tire Example
5-47
(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 at. If your vehicle has a compact
spare tire, seeCompact Spare Tire on page 5-73
andIf a Tire Goes Flat on page 5-62.(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 letters
and numbers following the DOT (Department of
Transportation) code is the Tire Identi cation 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 in ated to 60 psi (420 kPa).
For more information on tire pressure and in ation
seeIn ation - Tire Pressure on page 5-52.
(F) Tire Size:A combination of letters and numbers
de ne a tire’s width, height, aspect ratio, construction
type and service description. The letter T as the
rst 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 speci c tire performance criteria have a TPC
speci cation code molded onto the sidewall. GM’s TPC
speci cations meet or exceed all federal safety
guidelines. Compact Spare Tire Example
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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 certi ed
to carry. The load index can range from 1 to 279. The
speed rating is the maximum speed a tire is certi ed
to carry a load. Speed ratings range from A to Z.
5-49
A Tire and Loading Information label is attached to the
vehicle’s center pillar (B-pillar), below the driver’s
door latch. This label shows your vehicle’s original
equipment tires and the correct in ation pressures for
your tires when they are cold. The recommended
cold tire in ation 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 4-31. 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 5-73.
How to Check
Use a good quality pocket-type gage to check tire
pressure. You cannot tell if your tires are properly
in ated simply by looking at them. Radial tires may look
properly in ated even when they are under-in ated.
Check the tire’s in ation 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 in ation pressure matches
the recommended pressure on the Tire and Loading
Information label, no further adjustment is necessary.
If the in ation pressure is low, add air until you reach
the recommended amount.
If you over ll 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.
5-53