GMC 2007 Sierra - Manual (Page 565)

CAUTION: (Continued)
3. If you have a four-wheel-drive vehicle,
be sure the transfer case is in a drive
gear – not in NEUTRAL.
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 your vehicle has a flat tire, use the following
example as a guide to assist you in the placement
of the wheel blocks.
The following information will tell you next how to
use the jack and change a tire.
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