GMC Sierra Denali 2006 Owner's Manual page 364

3. Loosen the cable by turning the wheel wrench
counterclockwise three or four turns.
4. Repeat this procedure at least two times. If the
spare tire lowers to the ground, continue with
Step 5 of Removing the Spare Tire and Tools on
page 5-72.
5. Turn the wrench counterclockwise until
approximately 6 inches (15 cm) of cable is exposed.
6. Stand the wheel blocks on their shortest ends, with
the backs facing each other.
5-84
7. Place the bottom edge
of the jack (A) on the
wheel blocks (B),
separating them so that
the jack is balanced
securely.
8. Attach the jack handle, extension, and wheel
wrench to the jack and place it (with the wheel
blocks) under the vehicle towards the front of the
rear bumper.