2004 GMC YUKON tires

Highway Hypnosis
Is there actually such a condition as “highway hypnosis”?
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 inless than a second,and you could
crash and be injured.
What can you do about highway hypnosis? First, be
aware that it can happen.
Then here are some tips:
Make sure your vehicle is well ventilated, with a
comfortably cool interior.
Keep your eyes moving. Scan the road ahead and
to the sides. Check your mirrors and your
instruments frequently.
If you get sleepy, pull off the road into a rest,
service or parking area and take a nap, get some
exercise, or both. For safety, treat drowsiness
on the highway as an emergency.
Hill and Mountain Roads
Driving on steep hills or mountains is different from
driving in at or rolling terrain.
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. SeeOff-Road
Driving on page 4-22for 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.
You may see highway signs on mountains that warn
of special problems. Examples are long grades,
passing or no-passing zones, a falling rocks area or
winding roads. Be alert to these and take appropriate
action.
4-45

Driving on Snow or Ice
Most of the time, those places where your tires meet
the road probably have good traction.
However, if there is snow or ice between your tires and
the road, you can have a very slippery situation. You
will have a lot less traction or “grip” and will 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 may 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.
If you have traction assist, keep the system on. It will
improve your ability to accelerate when driving on
a slippery road. But you can turn the traction system off
if your vehicle ever gets stuck in sand, mud, ice or
snow. SeeIf You Are Stuck: In Sand, Mud, Ice or Snow
on page 4-50. Even though your vehicle has a traction
system, you will want to slow down and adjust your
driving to the road conditions. SeeTraction Assist
System (TAS) on page 4-9.
If you do not have a traction system, 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.
4-47

Then, shut the engine off and close the window almost
all the way to preserve the heat. Start the engine
again and repeat this only when you feel really
uncomfortable from the cold. But do it as little as
possible. Preserve the fuel as long as you can. To help
keep warm, you can get out of the vehicle and do
some fairly vigorous exercises every half hour or so until
help comes.
If You Are Stuck: In Sand, Mud, Ice
or Snow
In order to free your vehicle when it is stuck, you will
need to spin the wheels, but you do not want to
spin your wheels too fast. The method known as
“rocking” can help you get out when you are stuck, but
you must use caution.
{CAUTION:
If you let your tires spin at high speed, they
can explode, and you or others could be
injured. And, the transmission or other parts of
the vehicle can overheat. That could cause an
engine compartment re or other damage.
When you are stuck, spin the wheels as little
as possible. Do not spin the wheels above
35 mph (55 km/h) as shown on the
speedometer.
Notice:Spinning your wheels can destroy parts of
your vehicle as well as the tires. If you spin the
wheels too fast while shifting your transmission
back and forth, you can destroy your transmission.
For information about using tire chains on your
vehicle, seeTire Chains on page 5-82.
4-50

Tire and Loading Information Label
A. Vehicle Capacity Weight
The Tire and Loading Information label is attached to
the center pillar, near the driver’s door latch. Vehicles
without a center pillar will have the Tire and Loading
Information label attached to the driver’s door edge. This
label lists the number of people that can be in your
vehicle and the total weight it can carry. This weight is
called the vehicle capacity weight.
The Tire and Loading Information label also tells you
the size and recommended ination pressure for
the original equipment tires on your vehicle. For more
information on tires and ination seeTires on page 5-63
andInation - Tire Pressure on page 5-72.If your vehicle does not have the Tire and Loading
Information label, the Certication/Tire label shows the
tire size and recommended ination pressures
needed to obtain the Gross Vehicle Weight Rating
(GVWR) and the Gross Axle Weight Rating (GAWR) for
the front and rear axles. See “Certication/Tire Label”
later in this section.
Steps for Determining Correct Load Limit
1. Locate the statement “The combined weight of
occupants and cargo should never exceed XXX
pounds” on your vehicle placard.
2. Determine the combined weight of the driver and
passengers that will be riding in your vehicle.
3. Subtract the combined weight of the driver and
passengers from XXX kilograms or XXX pounds.
4. The resulting gure equals the available amount of
cargo and luggage load capacity. For example, if the
“XXX” amount equals 1400 lbs. and there will be ve
150 lb. passengers in your vehicle, the amount of
available cargo and luggage load capacity is 650 lbs.
(1400−750 (5 x 150) = 650 lbs.).
5. Determine the combined weight of luggage and
cargo being loaded on the vehicle. That weight
may not safely exceed the available cargo
and luggage load capacity calculated in Step 4.
4-57

Loading Your Vehicle
Item Description Total
AVehicle Capacity Weight
for Example 3 =1,000 lbs (453 kg)
BSubtract Occupant
Weight 200 lbs
(91kg)x5=1,000 lbs (453 kg)
CAvailable Cargo
Weight =0 lbs. (0 kg)
Refer to your vehicle’s tire and loading information label
for specic information about your vehicle’s capacity
weight and seating positions. The combined weight of
the driver, passengers and cargo should never
exceed your vehicle’s capacity weight.
Certication/Tire Label
The Certication/Tire label is found on the rear edge of
the driver’s door or in the Incomplete Vehicle
Document in the cab.
The label shows the size of your original tires and the
ination pressures needed to obtain the gross weight
capacity of your vehicle. This is called the GVWR (Gross
Vehicle Weight Rating). The GVWR includes the
weight of the vehicle, all occupants, fuel and cargo. Example 3
4-59

Then, during the rst 500 miles (800 km) that you
tow a trailer, don’t drive over 50 mph (80 km/h)
and don’t make starts at full throttle. This helps your
engine and other parts of your vehicle wear in at
the heavier loads.
You can tow in DRIVE (D). You may want to shift
the transmission to THIRD (3) or, if necessary, a
lower gear selection if the transmission shifts
too often (e.g., under heavy loads and/or hilly
conditions). See “Tow/Haul Mode” later in
this section.
Three important considerations have to do with weight:
The weight of the trailer
The weight of the trailer tongue
The weight on your vehicle’s tires
Tow/Haul Mode
Tow/Haul is a feature that assists when pulling a heavy
trailer or a large or heavy load. The purpose of the
Tow/Haul mode is to:
Reduce the frequency and improve the predictability
of transmission shifts when pulling a heavy trailer or
a large or heavy load.
Provide the same solid shift feel when pulling a
heavy trailer or a large or heavy load as when
the vehicle is unloaded.
Improve control of vehicle speed while requiring
less throttle pedal activity when pulling a heavy
trailer or a large or heavy load.
Your vehicle may be equipped with a button at the end of
the shift lever which, when pressed, enables tow/haul.
Your vehicle may be equipped with Autoride™
®which
further improves your vehicle’s ride while towing. See
Autoride™ on page 4-62for more information. When the
button is pressed, a light on the instrument panel will
illuminate to indicate that Tow/Haul has been selected.
Tow/Haul may be turned off by pressing the button again,
at which time the indicator light on the instrument panel
will turn off. The vehicle will automatically turn off Tow/
Haul every time it is started.
4-64

Do not exceed the maximum allowable tongue weight
for your vehicle. Choose the shortest hitch extension
that will position the hitch ball closest to the vehicle. This
will help reduce the effect of trailer tongue weight on
the rear axle.
After you have loaded the trailer, weigh the trailer and
then the tongue separately, to see if the weights
are proper. If they are not, you may be able to get them
right by moving some items around in the trailer.
Total Weight on Your Vehicle’s Tires
Be sure your vehicle’s tires are inated to the upper limit
for cold tires. You’ll nd these numbers on the
Certication label at the rear edge of the driver’s door or
see Loading Your Vehicle for more information. Then
be sure you don’t go over the GVW limit for your vehicle,
or the GAWR, including the weight of the trailer
tongue. If you use a weight distributing hitch, make sure
you don’t go over the rear axle limit before you apply
the weight distribution spring bars.
Hitches
It’s important to have the correct hitch equipment.
Crosswinds, large trucks going by and rough roads are
a few reasons why you will need the right hitch.
Weight Distributing Hitches and Weight
Carrying Hitches
When using a weight-distributing hitch, the hitch must
be adjusted so the distance (A) remains the same both
before and after coupling the trailer to the tow vehicle.
If you use a step-bumper hitch, the bumper could
be damaged in sharp turns. Make sure there is ample
room when turning to avoid contact between the
trailer and the bumper.(A) Body to Ground Distance (B) Front of Vehicle
4-69