Hummer 2008 H2 Owner's Manual page 415

CAUTION:
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Changing a tire can be dangerous. The vehicle
can slip off the jack and roll over or fall on you
or other people. You and they could be badly
injured or even killed. Find a level place to
change your tire. To help prevent the vehicle
from moving:
1. Set the parking brake firmly.
2. Put the shift lever in PARK (P).
3. 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, you can 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 you have a flat tire, use the following example as a
guide to assist you in the placement of wheel blocks.
The following steps will tell you next how to use the
jack and change a tire.
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