See also:

If the Vehicle Is Stuck
Slowly and cautiously spin the wheels to free the vehicle when stuck in sand, mud, ice, or snow. If stuck too severely for the traction system to free the vehicle, turn the traction system off an ...

Diagnostics
OnStar Vehicle Diagnostics will perform a vehicle check every month. It will check the engine, transmission, antilock brakes, and major vehicle systems. It also checks the tire pressures, if the v ...

Traction – AA, A, B, C
The traction grades, from highest to lowest, are AA, A, B, and C. Those grades represent the tire's ability to stop on wet pavement as measured under controlled conditions on specified gov ...