GM Service Manual Online
For 1990-2009 cars only

In order to free your vehicle when it is stuck, you will need to spin the wheels, but you do not want to spin the 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 vehicle's 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 fire 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 the wheels can destroy parts of your vehicle as well as the tires. If you spin the wheels too fast while shifting the transmission back and forth, you can destroy the transmission.