2007 GMC SIERRA Owner's Manual

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 reexes are tuned for driving
on dry pavement. If your vehicle has four-wheel
drive, seeFour-Wheel Drive on page 147for
transfer case mode selection.
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 uid
reservoir 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.
{CAUTION:
Wet brakes can cause accidents. They
may 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 the brake pedal
lightly until the brakes work normally.
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 cannot, try
to slow down before you hit them.
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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 is standing on the road. If you can
see reections from trees, telephone poles,
or other vehicles, and raindrops dimple 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 the engine’s air intake
and badly damage the engine. Never drive
through water that is slightly lower than the
underbody of your vehicle. If you cannot avoid
deep puddles or standing water, drive
through them very slowly.
410

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. See
Tires on page 550.
411

City Driving
One of the biggest problems with city streets is
the amount of traffic on them. You will want
to watch out for what the other drivers are doing
and pay attention to traffic signals.Here are ways to increase your safety in city
driving:
Know the best way to get to where you are
going. Get a city map and plan your trip
into an unknown part of the city just as you
would for a cross-country trip.
Try to use the freeways that rim and crisscross
most large cities. You will save time and
energy. SeeFreeway Driving on page 413.
Treat a green light as a warning signal. A
traffic light is there because the corner is
busy enough to need it. When a light turns
green, and just before you start to move,
check both ways for vehicles that have not
cleared the intersection or may be running the
red light.
412

Freeway Driving
Mile for mile, freeways — also called thruways,
parkways, expressways, turnpikes, or
superhighways — are the safest of all roads. But
they have their own special rules.The most important advice on freeway driving is:
Keep up with traffic and keep to the right.
Drive at the same speed most of the other drivers
are driving. Too-fast or too-slow driving breaks
a smooth traffic ow. Treat the left lane on
a freeway as a passing lane.
At the entrance, there is usually a ramp that leads
to the freeway. If you have a clear view of the
freeway as you drive along the entrance ramp, you
should begin to check traffic. Try to determine
where you expect to blend with the ow. Try to
merge into the gap at close to the prevailing speed.
Switch on your turn signal, check your mirrors, and
glance over your shoulder as often as necessary.
Try to blend smoothly with the traffic ow.
Once you are on the freeway, adjust your
speed to the posted limit or to the prevailing rate
if it is slower. Stay in the right lane unless you want
to pass.
413

Before changing lanes, check your mirrors. Then
use your turn signal.
Just before you leave the lane, glance quickly
over your shoulder to make sure there is not
another vehicle in your blind spot.
Once you are moving on the freeway, make
certain you allow a reasonable following distance.
Expect to move slightly slower at night.
When you want to leave the freeway, move to the
proper lane well in advance. If you miss your
exit, do not, under any circumstances, stop and
back up. Drive on to the next exit.
The exit ramp can be curved, sometimes quite
sharply. The exit speed is usually posted.
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 — such
as after a day’s work — 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.
414

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 inated 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 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 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.
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 vehicle’s mirrors
and 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.
415

Hill and Mountain Roads
Driving on steep hills or mountains is different
from driving in at or rolling terrain.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 on page 390for 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.
{CAUTION:
If you do not shift down, the 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 the engine assist
the brakes on a steep downhill slope.
416