GMC Sierra Denali Owner's Manual page 252

Rocking Your Vehicle To Get It Out
First, turn your steering wheel left and right. That will
clear the area around your front wheels. Then shift back
and forth between REVERSE (R) and a forward gear,
spinning the wheels as little as possible. Release
the accelerator pedal while you shift, and press lightly
on the accelerator pedal when the transmission is
in gear. By slowly spinning your wheels in the forward
and reverse directions, you will cause a rocking
motion that may free your vehicle. If that doesn't get
you out after a few tries, you may need to be towed out.
Or, you can use your recovery hooks if your vehicle
has them. If you do need to be towed out, see Towing
Your Vehicle on page 4-45.
Using the Recovery Hooks
I
Your vehicle is equipped with recovery hooks. The
hooks are provided at the front of your vehicle. You may
need to use them if you're stuck off-road and need to
be pulled to some place where you can continue driving.
4-43