Tires GMC SIERRA 2004 User Guide

Loading Your Vehicle for Off-Road
Driving
There are some important things to remember about
how to load your vehicle.
·The heaviest things should be on the load ¯oor and
forward of your rear axle. Put heavier items as far
forward as you can.
·Be sure the load is secured properly, so driving on
the off-road terrain does not toss things around.
{CAUTION:
·Cargo on the load ¯oor piled higher than
the seatbacks can be thrown forward
during a sudden stop. You or your
passengers could be injured. Keep cargo
below the top of the seatbacks.
·Unsecured cargo on the load ¯oor can be
tossed about when driving over rough
terrain. You or your passengers can be
struck by ¯ying objects. Secure the cargo
properly.
·Heavy loads on the roof raise the vehicle's
center of gravity, making it more likely to
roll over. You can be seriously or fatally
injured if the vehicle rolls over. Put heavy
loads inside the cargo area, not on the
roof. Keep cargo in the cargo area as far
forward and low as possible.
You will ®nd other important information in this manual.
See
Loading Your Vehicle on page 4-57andTires
on page 5-76.
4-23

·Never go downhill with the transmission in
NEUTRAL (N), or with the clutch pedal pressed
down in a manual shift. This is called
ªfree-wheeling.º Your brakes will have to do all the
work and could overheat and fade.
Q:Am I likely to stall when going downhill?
A:It is much more likely to happen going uphill. But if
it happens going downhill, here is what to do.
·Stop your vehicle by applying the regular brakes.
Apply the parking brake.
·Shift to PARK (P) (or to neutral with the manual
transmission) and, while still braking, restart the
engine.
·Shift back to a low gear, release the parking brake,
and drive straight down.
·If the engine will not start, get out and get help.
Driving Across an Incline
Sooner or later, an off-road trail will probably go across
the incline of a hill. If this happens, you have to
decide whether to try to drive across the incline. Here
are some things to consider:
·A hill that can be driven straight up or down may be
too steep to drive across. When you go straight up
or down a hill, the length of the wheel base (the
distance from the front wheels to the rear wheels)
reduces the likelihood the vehicle will tumble
end over end. But when you drive across an incline,
the much more narrow track width (the distance
between the left and right wheels) may not prevent
the vehicle from tilting and rolling over. Also,
driving across an incline puts more weight on the
downhill wheels. This could cause a downhill
slide or a rollover.
·Surface conditions can be a problem when you
drive across a hill. Loose gravel, muddy spots,
or even wet grass can cause your tires to slip
sideways, downhill. If the vehicle slips sideways,
it can hit something that will trip it (a rock, a rut, etc.)
and roll over.
·Hidden obstacles can make the steepness of the
incline even worse. If you drive across a rock with the
uphill wheels, or if the downhill wheels drop into a rut
or depression, your vehicle can tilt even more.
4-32

Driving in Mud, Sand, Snow or Ice
When you drive in mud, snow or sand, your wheels will
not get good traction. You can not accelerate as
quickly, turning is more difficult, and you will need longer
braking distances.
It is best to use a low gear when you are in mud Ð the
deeper the mud, the lower the gear. In really deep
mud, the idea is to keep your vehicle moving so you do
not get stuck.
When you drive on sand, you will sense a change in
wheel traction. But it will depend upon how loosely
packed the sand is. On loosely packed sand (as
on beaches or sand dunes) your tires will tend to sink
into the sand. This has an effect on steering,
accelerating and braking. Drive at a reduced speed and
avoid sharp turns or abrupt maneuvers.
Hard packed snow and ice offer the worst tire traction.
On these surfaces, it is very easy to lose control.
On wet ice, for example, the traction is so poor that you
will have difficulty accelerating. And if you do get
moving, poor steering and difficult braking can cause
you to slide out of control.{CAUTION:
Driving on frozen lakes, ponds or rivers can be
dangerous. Underwater springs, currents
under the ice, or sudden thaws can weaken the
ice. Your vehicle could fall through the ice and
you and your passengers could drown. Drive
your vehicle on safe surfaces only.
4-35

Driving in Water
Heavy rain can mean ¯ash ¯ooding, and ¯ood waters
demand extreme caution.
Find out how deep the water is before you drive through
it. If it is deep enough to cover your wheel hubs,
axles or exhaust pipe, do not try it Ð you probably will
not get through. Also, water that deep can damage
your axle and other vehicle parts.
If the water is not too deep, drive slowly through it. At
faster speeds, water splashes on your ignition
system and your vehicle can stall. Stalling can also
occur if you get your tailpipe under water. And, as long
as your tailpipe is under water, you will never be
able to start your engine. When you go through water,
remember that when your brakes get wet, it may
take you longer to stop.{CAUTION:
Driving through rushing water can be
dangerous. Deep water can sweep your vehicle
downstream and you and your passengers
could drown. If it is only shallow water, it can
still wash away the ground from under your
tires, and you could lose traction and roll the
vehicle over. Do not drive through rushing
water.
See
Driving in Rain and on Wet Roads on page 4-39for
more information on driving through water.
4-36

After Off-Road Driving
Remove any brush or debris that has collected on the
underbody, chassis or under the hood. These
accumulations can be a ®re hazard.
After operation in mud or sand, have the brake linings
cleaned and checked. These substances can cause
glazing and uneven braking. Check the body structure,
steering, suspension, wheels, tires and exhaust
system for damage. Also, check the fuel lines and
cooling system for any leakage.
Your vehicle will require more frequent service due to
off-road use. Refer to the Maintenance Schedule
for additional information.
Driving at Night
Night driving is more dangerous than day driving.
One reason is that some drivers are likely to be
impaired Ð by alcohol or drugs, with night vision
problems, or by fatigue.
4-37

Driving in Rain and on Wet Roads
Rain and wet roads can mean driving trouble. On a wet
road, you can not stop, accelerate or turn as well
because your tire-to-road traction is not as good as on
dry roads. And, if your tires do not have much tread
left, you will get even less traction. It is always wise to
go slower and be cautious if rain starts to fall while
you are driving. The surface may get wet suddenly when
your re¯exes are tuned for driving on dry pavement.The heavier the rain, the harder it is to see. Even if your
windshield wiper blades are in good shape, a heavy
rain can make it harder to see road signs and
traffic signals, pavement markings, the edge of the road
and even people walking.
It is wise to keep your wiping equipment in good shape
and keep your windshield washer tank ®lled with
washer ¯uid. Replace your windshield wiper inserts
when they show signs of streaking or missing areas on
the windshield, or when strips of rubber start to
separate from the inserts.
4-39

Driving too fast through large water puddles or even
going through some car washes can cause problems,
too. The water may affect your brakes. Try to avoid
puddles. But if you can not, try to slow down before you
hit them.
{CAUTION:
Wet brakes can cause accidents. They will not
work as well in a quick stop and may cause
pulling to one side. You could lose control of
the vehicle.
After driving through a large puddle of water
or a car wash, apply your brake pedal lightly
until your brakes work normally.
Hydroplaning
Hydroplaning is dangerous. So much water can build up
under your tires that they can 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.
Hydroplaning does not happen often. But it can if your
tires do not have much tread or if the pressure in
one or more is low. It can happen if a lot of water isstanding on the road. If you can see re¯ections from
trees, telephone poles or other vehicles, and raindrops
ªdimpleº the water's surface, there could be
hydroplaning.
Hydroplaning usually happens at higher speeds. There
just is not a hard and fast rule about hydroplaning.
The best advice is to slow down when it is raining.
Driving Through Deep Standing Water
Notice:If you drive too quickly through deep
puddles or standing water, water can come in
through your engine's air intake and badly damage
your engine. Never drive through water that is
slightly lower than the underbody of your vehicle. If
you can not avoid deep puddles or standing
water, drive through them very slowly.
4-40

Driving Through Flowing Water
{CAUTION:
Flowing or rushing water creates strong forces.
If you try to drive through ¯owing water, as you
might at a low water crossing, your vehicle can
be carried away. As little as six inches of
¯owing water can carry away a smaller vehicle.
If this happens, you and other vehicle
occupants could drown. Do not ignore police
warning signs, and otherwise be very cautious
about trying to drive through ¯owing water.
Some Other Rainy Weather Tips
·Turn on your low-beam headlamps ± not just your
parking lamps ± to help make you more visible to
others.
·Besides slowing down, allow some extra following
distance. And be especially careful when you pass
another vehicle. Allow yourself more clear room
ahead, and be prepared to have your view restricted
by road spray.
·Have good tires with proper tread depth. SeeTires
on page 5-76
.
4-41

Reduce your speed according to your speedometer, not
to your sense of motion. After driving for any distance
at higher speeds, you may tend to think you are
going slower than you actually are.
Before Leaving on a Long Trip
Make sure you are ready. Try to be well rested. If you
must start when you are not fresh Ð such as after
a day's work Ð do not plan to make too many miles that
®rst part of the journey. Wear comfortable clothing
and shoes you can easily drive in.
Is your vehicle ready for a long trip? If you keep it
serviced and maintained, it is ready to go. If it needs
service, have it done before starting out. Of course, you
will ®nd experienced and able service experts in GM
dealerships all across North America. They will be ready
and willing to help if you need it.
Here are some things you can check before a trip:
·Windshield Washer Fluid:Is the reservoir full? Are
all windows clean inside and outside?
·Wiper Blades:Are they in good shape?
·Fuel, Engine Oil, Other Fluids:Have you checked
all levels?
·Lamps:Are they all working? Are the lenses clean?
·Tires:They are vitally important to a safe,
trouble-free trip. Is the tread good enough for
long-distance driving? Are the tires all in¯ated to the
recommended pressure?
·Weather Forecasts:What is the weather outlook
along your route? Should you delay your trip a
short time to avoid a major storm system?
·Maps:Do you have up-to-date maps?
Highway Hypnosis
Is there actually such a condition as ªhighway
hypnosisº? Or is it just plain falling asleep at the wheel?
Call it highway hypnosis, lack of awareness, or
whatever.
There is something about an easy stretch of road with
the same scenery, along with the hum of the tires on the
road, the drone of the engine, and the rush of the
wind against the vehicle that can make you sleepy. Do
not let it happen to you! If it does, your vehicle can
leave the road in
less than a second,and you could
crash and be injured.
What can you do about highway hypnosis? First, be
aware that it can happen.
4-44

If you drive regularly in steep country, or if you are
planning to visit there, here are some tips that can make
your trips safer and more enjoyable. See
Off-Road
Driving with Your Four-Wheel-Drive Vehicle on
page 4-20
for information about driving off-road.
·Keep your vehicle in good shape. Check all ¯uid
levels and also the brakes, tires, cooling system
and transmission. These parts can work hard
on mountain roads.
·Know how to go down hills. The most important
thing to know is this: let your engine do some of
the slowing down. Shift to a lower gear when you go
down a steep or long hill.
{CAUTION:
If you do not shift down, your brakes could get
so hot that they would not work well. You
would then have poor braking or even none
going down a hill. You could crash. Shift down
to let your engine assist your brakes on a
steep downhill slope.
{CAUTION:
Coasting downhill in NEUTRAL (N) or with the
ignition off is dangerous. Your brakes will have
to do all the work of slowing down. They could
get so hot that they would not work well. You
would then have poor braking or even none
going down a hill. You could crash. Always
have your engine running and your vehicle in
gear when you go downhill.
·Know how to go uphill. You may want to shift down
to a lower gear. The lower gears help cool your
engine and transmission, and you can climb the hill
better.
·Stay in your own lane when driving on two-lane
roads in hills or mountains. Do not swing wide
or cut across the center of the road. Drive at speeds
that let you stay in your own lane.
·As you go over the top of a hill, be alert. There
could be something in your lane, like a stalled car or
an accident.
4-46