GMC 2008 Sierra 1500 Pickup Owner's Manual page 396

4. Turn the wheel wrench (H) counterclockwise to
lower the spare tire to the ground. Continue to
turn the wheel wrench until the spare tire can
be pulled out from under the vehicle.
If the spare tire does not lower to the ground,
the secondary latch is engaged causing the tire
not to lower. See Secondary Latch System
on page 5-91.
5-84
5. Use the wheel wrench
which has a hook
that lets you pull the
hoist cable toward you
to assist in reaching
the spare tire.
6. Tilt the tire toward the vehicle with some slack
in the cable to allow access to the tire/wheel
retainer (D). Separate the retainer from the
guide pin by sliding the retainer up the pin while
pressing down on the latch.