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.
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 thetires 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.
If the vehicle has the Antilock Brake System (ABS),
remember: It helps avoid only the braking skid. If the
vehicle does not have ABS, then in a braking skid,
where the wheels are no longer rolling, release enough
pressure on the brakes to get the wheels rolling again.
This restores steering control. Push the brake pedal
down steadily when you have to stop suddenly. As long
as the wheels are rolling, you will have steering control.
Driving at Night
Night driving is more dangerous than day driving
because some drivers are likely to be impaired —by
alcohol or drugs, with night vision problems, or by
fatigue.
Night driving tips include:
.Drive defensively.
.Do not drink and drive.
.Reduce headlamp glare by adjusting the inside
rearview mirror.
.Slow down and keep more space between you and
other vehicles because headlamps can only light
up so much road ahead.
5-8
.Watch for animals.
.When tired, pull off the road.
.Do not wear sunglasses.
.Avoid staring directly into approaching headlamps.
.Keep the windshield and all glass on your vehicle
clean—inside and out.
.Keep your eyes moving, especially during turns or
curves.
No one can see as well at night as in the daytime.
But, as we get older, these differences increase.
A 50-year-old driver might need at least twice as much
light to see the same thing at night as a 20-year-old.
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.
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WARNING: (Continued)
.Overinflated 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 the tire's tread is badly worn, or if your
vehicle's tires have been damaged,
replace them.
Tire Sidewall Labeling
Useful information about a tire is molded into its
sidewall. The examples below show a typical
passenger car tire and a compact spare tire
sidewall.
Passenger Car Tire Example
(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.
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(B) 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.
(C) Tire Identification 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.
(D) Tire Ply Material
:The type of cord and
number of plies in the sidewall and under the
tread.
(E) 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 6‑65.
(F) Maximum Cold Inflation Load Limit
:
Maximum load that can be carried and the
maximum pressure needed to support that load.
For information on recommended tire pressure
see Inflation - Tire Pressure
on page 6‑57and
Loading the Vehicle
on page 5‑14.
Compact Spare Tire Example
(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
on page 6‑78andIf a
Tire Goes Flat
on page 6‑69.
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(B) Tire Ply Material:The type of cord and
number of plies in the sidewall and under the
tread.
(C) Tire Identification 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 Inflation Load Limit
:
Maximum load that can be carried and the
maximum pressure needed to support that load.
See Compact Spare Tire
on page 6‑78and
Loading the Vehicle
on page 5‑14.
(E) Tire Inflation
:The temporary use tire or
compact spare tire should be inflated to 60 psi
(420 kPa). For more information on tire pressure
and inflation see Inflation - Tire Pressure
on
page 6‑57
.
(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.
Tire Size
The following illustration shows an example of a
typical passenger car tire size.
(A) Passenger (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% as high as it is wide.
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(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.
Tire Terminology and Definitions
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. See Inflation - Tire Pressure
on
page 6‑57
.
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
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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
inflated simply by looking at them. Radial tires
may look properly inflated even when they are
under‐inflated. 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.
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.
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 inflated to the inflation
pressure recommended by the vehicle manufacturer on
the vehicle placard or tire inflation pressure label. (If
your vehicle has tires of a different size than the size
indicated on the vehicle placard or tire inflation pressure
label, you should determine the proper tire inflation
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 significantly under‐inflated.
Accordingly, when the low tire pressure telltale
illuminates, you should stop and check your tires as
soon as possible, and inflate them to the proper
pressure. Driving on a significantly under‐inflated tire
causes the tire to overheat and can lead to tire failure.
Under‐inflation also reduces fuel efficiency and tire
tread life, and may affect the vehicle's handling and
stopping ability.
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When It Is Time for New Tires
Various factors, such as maintenance, temperatures,
driving speeds, vehicle loading, and road conditions
influence when you need new tires.
One way to tell when it is
time for new tires is to
check the treadwear
indicators, which will
appear when your tires
have only 1/16 inch
(1.6 mm) or less of tread
remaining.
You need new tires if any of the following statements
are true:
.You can see the indicators at three or more places
around the tire.
.You can see cord or fabric showing through the
tire's rubber.
.The tread or sidewall is cracked, cut, or snagged
deep enough to show cord or fabric.
.The tire has a bump, bulge, or split.
.The tire has a puncture, cut, or other damage that
cannot be repaired well because of the size or
location of the damage.
The rubber in tires degrades over time, even if they are
not being used. This is also true for the spare tire,
if your vehicle has one. Multiple conditions affect how
fast this aging takes place, including temperatures,
loading conditions, and inflation pressure maintenance.
With proper care and maintenance tires will typically
wear out before they degrade due to age. If you are
unsure about the need to replace your tires as they get
older, consult the tire manufacturer for more information.
Buying New Tires
GM has developed and matched specific tires for your
vehicle. If you need replacement tires, GM strongly
recommends that you get tires that are the same size,
brand, load range, speed rating, and construction type
(radial and bias‐belted tires) as your vehicle's original
tires. 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.
See Tire Sidewall Labeling
on page 6‑51for additional
information.
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