2009 HUMMER H2 wheel

Surface Obstacles:Unseen or hidden obstacles can
be hazardous. A rock, log, hole, rut, or bump can startle
you if you are not prepared for them. Often these
obstacles are hidden by grass, bushes, snow, or even
the rise and fall of the terrain itself.
Some things to consider:
Is the path ahead clear?
Will the surface texture change abruptly up ahead?
Does the travel take you uphill or downhill?
Will you have to stop suddenly or change direction
quickly?
When driving over obstacles or rough terrain, keep a rm
grip on the steering wheel. Ruts, troughs, or other surface
features can jerk the wheel out of your hands.
When driving over bumps, rocks, or other obstacles, the
wheels can leave the ground. If this happens, even with
one or two wheels, you cannot control the vehicle as well
or at all.
Because you will be on an unpaved surface, it is
especially important to avoid sudden acceleration,
sudden turns, or sudden braking.
Off-roading requires a different kind of alertness from
driving on paved roads and highways. There are no road
signs, posted speed limits, or signal lights. Use good
judgment about what is safe and what is not.
Crossing Obstacles
Approach Angle — a Key to Mobility
If you encounter a large dip in the terrain, do not
enter straight on; enter at an angle — 15° minimum
approach (A), 75° maximum approach angle (B). For
very large dips, ditches or small washes, coast in, using
the engine as a brake (transmission and transfer case
lowest gears). Then, use the low ranges in the
transmission and transfer case to power out.
4-23

Driving Uphill
Once you decide it is safe to drive up the hill:
Use transmission and transfer case low gear and
get a rm grip on the steering wheel.
Get a smooth start up the hill and try to maintain
speed. Not using more power than needed can
avoid spinning the wheels or sliding.
Let the traction system work to control any wheel
slippage. The traction control system allows for
moderate wheel spin with some capability to dig in
and power up the hill.
Do not continue if the vehicle shudders or exhibits
suspension hopping. This can cause damage to
the driveline or suspension components. Improper
driving technique is not covered by the vehicle
warranty.
{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 the speed as you approach the top of
the hill.
Attach a ag to the vehicle to be 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 headlamps even during the day to make the
vehicle more visible to oncoming traffic.
4-26

{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.
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 and apply the parking
brake.
If the engine is still running, shift the transmission to
R (Reverse), release the parking brake, and slowly
back down the hill in R (Reverse).
If the engine has stopped running, you need to
restart it. With the brake pedal pressed, apply
the parking brake. If the vehicle has an automatic
transmission, shift the transmission to P (Park).
Restart the engine. Then, shift to R (Reverse),
release the parking brake, and slowly back down
the hill as straight as possible in R (Reverse).
While backing down the hill, put your left hand on the
steering wheel at the 12 o’clock position so you can
tell if the wheels are straight and can maneuver as
you back down. It is best to back down the hill with
the wheels straight rather than in the left or right
direction. Turning the wheel too far to the left or right
will increase the possibility of a rollover.
4-27

Driving Downhill
When off-roading takes you downhill, consider:
How steep is the downhill? Will I be able to maintain
vehicle control?
What is the surface like? Smooth? Rough?
Slippery? Hard-packed dirt? Gravel?
Are there hidden surface obstacles? Ruts? Logs?
Boulders?
What is at the bottom of the hill? Is there a hidden
creek bank or even a river bottom with large rocks?
If you decide you can go down a hill safely, try to keep
the vehicle headed straight down. Use a low gear
so engine drag can help the brakes so they do not have
to do all the work. Descend slowly, keeping the
vehicle under control at all times.
{CAUTION:
Heavy braking when going down a hill can cause
your brakes to overheat and fade. This could cause
loss of control and a serious accident. Apply the
brakes lightly when descending a hill and use a low
gear to keep vehicle speed under control.Things not to do when driving down a hill:
When driving downhill, avoid turns that take you
across the incline of the hill. A hill that is not too
steep to drive down might be too steep to drive
across. The vehicle could roll over.
Never go downhill with the transmission in
N (Neutral), called free-wheeling. The brakes will
have to do all the work and could overheat
and fade.
Vehicles are much more likely to stall when going uphill,
but if it happens when going downhill:
1. Stop the vehicle by applying the regular brakes and
apply the parking brake.
2. Shift to P (Park). While still braking, restart the
engine.
3. Shift back to a low gear, release the parking brake,
and drive straight down.
4. If the engine will not start, get out and get help.
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Driving Across an Incline
An off-road trail will probably go across the incline of a
hill. To decide whether to try to drive across the
incline, consider the following:
{CAUTION:
Driving across an incline that is too steep will
make your vehicle roll over. You could be
seriously injured or killed. If you have any doubt
about the steepness of the incline, do not drive
across it. Find another route instead.
A hill that can be driven straight up or down
might be too steep to drive across. When going
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 driving across an
incline, the narrower track width — the distance
between the left and right wheels — might not
prevent the vehicle from tilting and rolling over.
Driving across an incline puts more weight on the
downhill wheels which could cause a downhill slide
or a rollover.
Surface conditions can be a problem. Loose gravel,
muddy spots, or even wet grass can cause the 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, the vehicle can tilt even more.
For these reasons, carefully consider whether to try to
drive across an incline. Just because the trail goes
across the incline does not mean you have to drive it.
The last vehicle to try it might have rolled over.
If you feel the vehicle starting to slide sideways, turn
downhill. This should help straighten out the vehicle and
prevent the side slipping. The best way to prevent
this is to “walk the course” rst, so you know what the
surface is like before driving it.
4-30

Stalling on an Incline
{CAUTION:
Getting out on the downhill (low) side of a vehicle
stopped across an incline is dangerous. If the
vehicle rolls over, you could be crushed or killed.
Always get out on the uphill (high) side of the
vehicle and stay well clear of the rollover path.
If the vehicle stalls when crossing an incline, be sure
you, and any passengers, get out on the uphill side, even
if the door there is harder to open. If you get out on the
downhill side and the vehicle starts to roll over, you will
be right in its path.
If you have to walk down the slope, stay out of the path
the vehicle will take if it does roll over.
Driving in Mud, Sand, Snow, or Ice
When you drive in mud, snow, or sand, the wheels do not
get good traction. Acceleration is not as quick, turning is
more difficult, and braking distances are longer.
It is best to use a low gear when in mud — the deeper
the mud, the lower the gear. In really deep mud,
keep the vehicle moving so it does not get stuck.When driving on sand, wheel traction changes. On
loosely packed sand, such as on beaches or sand
dunes, the tires will tend to sink into the sand. This
affects 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 the vehicle
does get moving, poor steering and difficult braking can
cause it 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.
4-31

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 driving through
it. Do not try it if it is deep enough to cover the wheel
hubs, axles, or exhaust pipe — you probably will not
get through. Deep water can damage the axle and
other vehicle parts. The vehicle is capable of depths up to
20 inches (50 cm). Know how to judge whether the water
is deeper than this before proceeding into it.If the water is not too deep, drive slowly through it. At
faster speeds, water splashes on the ignition system and
the vehicle can stall. Stalling can also occur if you get
the tailpipe under water. If the tailpipe is under
water, you will never be able to start the engine. When
going through water, remember that when the brakes
get wet, it might take longer to stop. SeeDriving in Rain
and on Wet Roads on page 4-34.
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 engine and oil
coolers for mud accumulation. Thoroughly and carefully
clean these devices to allow proper cooling. Check
the body structure, steering, suspension, wheels, tires,
and exhaust system for damage and check the fuel
lines and cooling system for any leakage.
The vehicle requires more frequent service due to
off-road use. Refer to the Maintenance Schedule for
additional information.
4-32

Winter Driving
Driving on Snow or Ice
Drive carefully when there is snow or ice between the
tires and the road, creating less traction or grip. Wet ice
can occur at about 32°F (0°C) when freezing rain
begins to fall, resulting in even less traction. Avoid
driving on wet ice or in freezing rain until roads can be
treated with salt or sand.
Drive with caution, whatever the condition. Accelerate
gently so traction is not lost. Accelerating too quickly
causes the wheels to spin and makes the surface under
the tires slick, so there is even less traction.
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.TheTraction Control System (TCS) on page 4-9
improves the ability to accelerate on slippery roads, but
slow down and adjust your driving to the road conditions.
When driving through deep snow, turn off the traction
control system to help maintain vehicle motion at lower
speeds.
TheAntilock Brake System (ABS) on page 4-5improves
vehicle stability during hard stops on a slippery roads,
but apply the brakes sooner than when on dry
pavement.
Allow greater following distance on any slippery road
and watch for slippery spots. Icy patches can occur on
otherwise clear roads in shaded areas. The surface
of a curve or an overpass can remain icy when
the surrounding roads are clear. Avoid sudden steering
maneuvers and braking while on ice.
Turn off cruise control, if equipped, on slippery surfaces.
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