2008 GMC ENVOY Traction

Getting Familiar with Off-Road Driving
It is a good idea to practice in an area that is safe
and close to home before you go into the wilderness.
Off-road driving does require some new and different
skills. Here is what we mean.
Tune your senses to different kinds of signals. Your
eyes, for example, need to constantly sweep the terrain
for unexpected obstacles. Your ears need to listen
for unusual tire or engine sounds. With your arms,
hands, feet, and body, you will need to respond to
vibrations and vehicle bounce.
Controlling your vehicle is the key to successful off-road
driving. One of the best ways to control your vehicle
is to control your speed. Here are some things to keep
in mind. At higher speeds:
You approach things faster and you have less time
to scan the terrain for obstacles.
You have less time to react.
You have more vehicle bounce when you drive over
obstacles.
You will need more distance for braking, especially
since you are on an unpaved surface.
{CAUTION:
When you are driving off-road, bouncing and
quick changes in direction can easily throw
you out of position. This could cause you to
lose control and crash. So, whether you are
driving on or off the road, you and your
passengers should wear safety belts.
Scanning the Terrain
Off-road driving can take you over many different kinds
of terrain. You need to be familiar with the terrain and its
many different features. Here are some things to
consider.
Surface Conditions:Off-roading can take you over
hard-packed dirt, gravel, rocks, grass, sand, mud, snow,
or ice. Each of these surfaces affects the steering,
acceleration, and braking of your vehicle in different
ways. Depending upon the kind of surface you are on,
you may experience slipping, sliding, wheel spinning,
delayed acceleration, poor traction, and longer braking
distances.
4-16

Driving on Off-Road Hills
Off-road driving often takes you up, down, or across a
hill. Driving safely on hills requires good judgment
and an understanding of what your vehicle can and
cannot do. There are some hills that simply cannot be
driven, no matter how well built the vehicle.
{CAUTION:
Many hills are simply too steep for any vehicle.
If you drive up them, you will stall. If you drive
down them, you cannot control your speed. If
you drive across them, you will roll over. You
could be seriously injured or killed. If you have
any doubt about the steepness, do not drive
the hill.
Approaching a Hill
When you approach a hill, you need to decide if it is
one of those hills that is just too steep to climb, descend,
or cross. Steepness can be hard to judge. On a very
small hill, for example, there may be a smooth, constantincline with only a small change in elevation where you
can easily see all the way to the top. On a large hill,
the incline may get steeper as you near the top, but you
may not see this because the crest of the hill is hidden
by bushes, grass, or shrubs.
Here are some other things to consider as you approach
a hill.
Is there a constant incline, or does the hill get
sharply steeper in places?
Is there good traction on the hillside, or will the
surface cause tire slipping?
Is there a straight path up or down the hill so you
will not have to make turning maneuvers?
Are there obstructions on the hill that can block your
path, such as boulders, trees, logs, or ruts?
What is beyond the hill? Is there a cliff, an
embankment, a drop-off, a fence? Get out and
walk the hill if you do not know. It is the smart
way to nd out.
Is the hill simply too rough? Steep hills often have
ruts, gullies, troughs, and exposed rocks because
they are more susceptible to the effects of erosion.
4-18

Driving Uphill
Once you decide you can safely drive up the hill, you
need to take some special steps.
Use a low gear and get a rm grip on the steering
wheel.
Get a smooth start up the hill and try to maintain
your speed. Do not use more power than you
need, because you do not want the wheels to
start spinning or sliding.
{CAUTION:
Turning or driving across steep hills can be
dangerous. You could lose traction, slide
sideways, and possibly roll over. You could
be seriously injured or killed. When driving up
hills, always try to go straight up.
Try to drive straight up the hill if at all possible.
If the path twists and turns, you might want to
nd another route.
Ease up on your speed as you approach the top of
the hill.
Attach a ag to the vehicle to make you more
visible to approaching traffic on trails or hills.
Sound the horn as you approach the top of the hill
to let opposing traffic know you are there.
Use your headlamps even during the day. They
make your vehicle more visible to oncoming traffic.
{CAUTION:
Driving to the top (crest) of a hill at full speed
can cause an accident. There could be a
drop-off, embankment, cliff, or even another
vehicle. You could be seriously injured or killed.
As you near the top of a hill, slow down and
stay alert.
There are some things you should do if the vehicle stalls,
or is about to stall, and you cannot make it up the hill:
Push the brake pedal to stop the vehicle and keep it
from rolling backwards. Also, apply the parking
brake.
If the engine is still running, shift the transmission to
REVERSE (R), release the parking brake, and slowly
back down the hill in REVERSE (R).
4-19

Driving in Mud, Sand, Snow, or Ice
When you drive in mud, snow, or sand, the wheels
will not get good traction. You cannot 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 — 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, such as
on beaches or sand dunes, the 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.
4-24

Driving in Water
{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.
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 the wheel hubs, axles,
or exhaust pipe, do not try it — you probably will not get
through. Also, water that deep can damage the axle
and other vehicle parts.If the water is not too deep, drive slowly through it.
At faster speeds, water splashes on the ignition system
and your vehicle can stall. Stalling can also occur if you
get the tailpipe under water. And, as long as the tailpipe
is under water, you will never be able to start the engine.
When you go through water, remember that when the
brakes get wet, it may take you longer to stop.
SeeDriving in Rain and on Wet Roads on page 4-27for
more information on driving through water.
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.
4-25

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 owing water.
{CAUTION:
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 owing 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 owing 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 uid reservoir lled.
Have good tires with proper tread depth. SeeTires
on page 5-57.
4-27

Winter Driving
Here are some tips for winter driving:
Have your vehicle in good shape for winter.
You might want to put winter emergency supplies in
your vehicle.
Include an ice scraper, a small brush or broom, a supply
of windshield washer uid, a rag, some winter outer
clothing, a small shovel, a ashlight, a red cloth, and
reective warning triangles. And, if you will be driving
under severe conditions, include a small bag of sand,
a piece of old carpet, or a couple of burlap bags to help
provide traction. Be sure you properly secure these
items in your vehicle.
Also seeTires on page 5-57.
Driving on Snow or Ice
Most of the time, those places where the tires meet the
road probably have good traction.
However, if there is snow or ice between the tires
and the road, you can have a very slippery situation.
You have a lot less traction, or grip, and need to be
very careful.What is the worst time for this? Wet ice. Very cold snow
or ice can be slick and hard to drive on. But wet ice can
be even more trouble because it can offer the least
traction of all. You can get wet ice when it is about
freezing, 32°F (0°C), and freezing rain begins to fall.
Try to avoid driving on wet ice until salt and sand crews
can get there.
Whatever the condition — smooth ice, packed, blowing,
or loose snow — drive with caution.
4-30

Accelerate gently. Try not to break the fragile traction.
If you accelerate too fast, the drive wheels will spin and
polish the surface under the tires even more.
The Antilock Brake System (ABS) improves your
vehicle’s stability when you make a hard stop on a
slippery road. Even though you have ABS, begin
stopping sooner than you would on dry pavement.
SeeAntilock Brake System (ABS) on page 4-4.
Allow greater following distance on any
slippery road.
Watch for slippery spots. The road might be ne
until you hit a spot that is covered with ice. On an
otherwise clear road, ice patches can appear in
shaded areas where the sun cannot reach, such as
around clumps of trees, behind buildings, or under
bridges. Sometimes the surface of a curve or an
overpass can remain icy when the surrounding roads
are clear. If you see a patch of ice ahead of you,
brake before you are on it. Try not to brake while you
are actually on the ice, and avoid sudden steering
maneuvers.
If You Are Caught in a Blizzard
If you are stopped by heavy snow, you could be in a
serious situation. You should probably stay with your
vehicle unless you know for sure that you are near help
and you can hike through the snow. Here are some things
to do to summon help and keep yourself and your
passengers safe:
Turn on the hazard warning ashers.
Tie a red cloth to your vehicle to alert police that you
have been stopped by the snow.
Put on extra clothing or wrap a blanket around you.
If you do not have blankets or extra clothing, make
body insulators from newspapers, burlap bags, rags,
oor mats — anything you can wrap around yourself
or tuck under your clothing to keep warm.
4-31