GMC 2013 Sierra Denali Owner's Manual page 380

3. Insert the hoist end (open
end) (F) of the extension through
the hole (G) in the rear bumper.
Be sure the hoist end of the
extension connects to the hoist
shaft. The ribbed square end of
the extension is used to lower
the spare tire.
4. Turn the wheel wrench
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.
5. Use the wheel wrench hook to
pull the hoist cable closer 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.
Tilt the retainer and pull it
through the center of the wheel
along with the cable and spring.
7. Put the spare tire near the
flat tire.