wheel HUMMER H3 2010 Owner's Guide

Driving and Operating 9-13
Scanning the Terrain
Off-road driving can take you over
many different kinds of terrain. Be
familiar with the terrain and its many
different features.
Surface Conditions:Off-roading
surfaces can be hard-packed dirt,
gravel, rocks, grass, sand, mud,
snow, or ice. Each of these surfaces
affects the vehicle's steering,
acceleration, and braking in different
ways. Depending on the surface,
slipping, sliding, wheel spinning,
delayed acceleration, poor traction,
and longer braking distances can
occur. 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 firm 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.

9-14 Driving and Operating
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. Roll The Tires Over Large Rocks
Do not straddle large rocks; drive
over them, letting the tire cover the
rock. The tread of the tire is thicker
and tougher than the sidewall of the
tire and is more resilient to impact
than underbody components.
Log Crossing
Using the proper technique,
the vehicle will cross logs up to
25.4 cm (10 inches) in diameter.
Approach the log at approximately a
15° angle (A) with the transmission
in 1 (First) and the transfer case in
Four‐Wheel‐Low Lock and
“walk”the vehicle over, one tire at a time.
It may be necessary to modulate
the brake pedal and accelerator to
avoid spin-out. Ease the vehicle
down from the log with the brake.
Driving on 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 the
vehicle can and cannot do. There
are some hills that simply cannot be
driven, no matter how well built the
vehicle.

Driving and Operating 9-15
{WARNING
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, decide if
it is 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,
constant incline 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
might not see this because the crest
of the hill is hidden by bushes,
grass, or shrubs.Consider this 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 find 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.See
Hill Start Assist (HSA)
on
page 9‑52for information on
vehicles stopped on a grade.
Driving Uphill
Once you decide it is safe to drive
up the hill:
.Use transmission and transfer
case low gear and get a firm 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.

Driving and Operating 9-17
.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.
Things not to do if the vehicle stalls,
or is about to stall, when going up
a hill:
.Never attempt to prevent a stall
by shifting into N (Neutral) to
rev-up the engine and regain
forward momentum. This will
not work. The vehicle can roll
backward very quickly and could
go out of control.
.Never try to turn around if about
to stall when going up a hill.
If the hill is steep enough to stall
the vehicle, it is steep enough
to cause it to roll over. If you
cannot make it up the hill, back
straight down the hill.
If, after stalling, you try to back
down the hill and decide you just
cannot do it, set the parking brake.
If the vehicle has an automatic
transmission, shift to P (Park). Turn
off the engine. Leave the vehicle
and go get some help. Exit on the
uphill side and stay clear of the path
the vehicle would take if it rolled
downhill. Do not shift the transfer
case to Neutral when you leave the
vehicle. Leave it in some gear.
{WARNING
Shifting the transfer case to
Neutral can cause your vehicle to
roll even if the transmission is in
P (Park). This is because the
Neutral position on the transfer
case overrides the transmission.
You or someone else could be
injured. If you are going to leave
your vehicle, set the parking
brake and shift the transmission
to P (Park). But do not shift the
transfer case to Neutral.

9-18 Driving and Operating
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.
{WARNING
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. With an automatic transmission, 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.

Driving and Operating 9-19
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:
{WARNING
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” first, so
you know what the surface is like
before driving it.

9-20 Driving and Operating
Stalling on an Incline
{WARNING
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.
{WARNING
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.

Driving and Operating 9-21
Driving in Water
{WARNING
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 flash flooding,
and flood 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 50 cm (20 inches). 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. See Driving on Wet
Roads on page 9‑22.
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 fire 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.

9-24 Driving and Operating
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 0°C
(32°F) 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.The
Antilock Brake System (ABS)
on page 9‑50improves vehicle
stability during hard stops on
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.Blizzard Conditions
Being stuck in snow can be a
serious situation. Stay with the
vehicle unless there is help nearby.
If possible, use the Roadside
Service
on page 13‑5. To get help
and keep everyone in the
vehicle safe:
.Turn on the hazard warning
flashers.
.Tie a red cloth to an outside
mirror.
{WARNING
Snow can trap engine exhaust
under the vehicle. This may
cause exhaust gases to get
inside. Engine exhaust contains
carbon monoxide (CO) which
cannot be seen or smelled. It can
cause unconsciousness and even
death.
(Continued)

9-26 Driving and Operating
If the Vehicle is Stuck
Slowly and cautiously spin the
wheels to free the vehicle when
stuck in sand, mud, ice, or snow.
If stuck too severely for the traction
system to free the vehicle, turn the
traction system off and use the
rocking method.
{WARNING
If the vehicle's tires spin at high
speed, they can explode, and you
or others could be injured. The
vehicle can overheat, causing an
engine compartment fire or other
damage. Spin the wheels as little
as possible and avoid going
above 55 km/h (35 mph) as
shown on the speedometer.
For information about using tire
chains on the vehicle, see Tire
Chains on page 10‑64.
Rocking the Vehicle to Get
it Out
Turn the steering wheel left and
right to clear the area around the
front wheels. Turn off any traction
system. Shift back and forth
between R (Reverse) and a forward
gear, or with a manual transmission,
between 1 (First) or 2 (Second) and
R (Reverse), spinning the wheels
as little as possible. To prevent
transmission wear, wait until the
wheels stop spinning before shifting
gears. Release the accelerator
pedal while shifting, and press
lightly on the accelerator pedal
when the transmission is in gear.
Slowly spinning the wheels in the
forward and reverse directions
causes a rocking motion that could
free the vehicle. If that does not get
the vehicle out after a few tries, it
might need to be towed out. The
recovery loops can be used. If the
vehicle does need to be towed out,
see Towing the Vehicle
on
page 10‑90. Recovery Loops
{WARNING
These loops, when used, are
under a lot of force. Keep people
away from the vicinity of the loops
and any chains or cables during
use. Always pull the vehicle
straight out. Never pull on the
loops at a sideways angle. The
loops could break off and you or
others could be injured from the
chain or cable snapping back.
Notice: Never use the recovery
loops to tow the vehicle. The
vehicle could be damaged and
it would not be covered by the
vehicle warranty.