GMC Sierra Denali 2009 Owner's Manual page 312

The Certification/Tire label also tells the maximum
weights for the front and rear axles, called
Gross Axle Weight Rating (GAWR). To find out
the actual loads on the front and rear axles, go to
a weigh station and weigh your vehicle. Your
dealer can help you with this. Be sure to spread
out your load equally on both sides of the
centerline.
Never exceed the GVWR for your vehicle, or the
GAWR for either the front or rear axle.
The Certification/Tire label also contains important
information about the Front Axle Reserve
Capacity.
CAUTION:
{
In the case of a sudden stop or collision,
things carried in the bed of your truck could
shift forward and come into the passenger
area, injuring you and others. If you put
things in the bed of your truck, you should
make sure they are properly secured.
4-36
CAUTION:
{
Do not load the vehicle any heavier than the
Gross Vehicle Weight Rating (GVWR), or
either the maximum front or rear Gross Axle
Weight Rating (GAWR). If you do, parts on
the vehicle can break, and it can change
the way your vehicle handles. These could
cause you to lose control and crash. Also,
overloading can shorten the life of the
vehicle.
Notice Overloading your vehicle may cause
:
damage. Repairs would not be covered by your
warranty. Do not overload your vehicle.
Using heavier suspension components to get
added durability might not change the vehicle's
weight ratings. Ask your dealer to help you
load your vehicle the right way.
If things are put inside your vehicle — like
suitcases, tools, packages, or anything else — they
go as fast as the vehicle goes. If you have to stop or
turn quickly, or if there is a crash, they will keep
going.