GMC 2010 Sierra Denali Owner's Manual page 461

WARNING: (Continued)
4. Turn off the engine and do not restart while
the vehicle is raised.
5. Do not allow passengers to remain in the
vehicle.
To be even more certain the vehicle will not move,
put blocks at the front and rear of the tire farthest
away from the one being changed. That would be
the tire on the other side, at the opposite end of
the vehicle.
When the vehicle has a flat tire (B), use the following
example as a guide to assist you in the placement of
wheel blocks (A).
A. Wheel Block
B. Flat Tire
The following information explains how to use the jack
and change a tire.
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