Hummer 2008 H3 Owner's Manual page 340

The spare tire is attached to the outside of the
swing-gate. To remove the spare tire:
1. If your vehicle has a spare tire cover release the
latch by pulling the latch straight back and turning
it away from the cover at the same time.
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Notice: Opening the endgate before completely
closing and latching the spare tire cover may result
in damage to your vehicle. Close and latch the
spare tire cover before opening the endgate to avoid
possible damage.
2. Remove the center
cap, if equipped, by
placing the flat end of
the wheel wrench
in the slot on the wheel
and gently pry the
center cap out.