Chevrolet 2008 Tahoe Owner's Manual page 454

Be sure the hoist end (J) of the extension (D)
connects to the hoist shaft (B). The ribbed square
end of the extension is used to lower the spare tire.
5. Turn the wheel wrench (E) counterclockwise to
lower the spare tire (H) 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 5-98
for more information.
5-90
4. Insert the open end of
the extension (J)
through the hole in
the rear bumper (I)
(hoist shaft
access hole).
6. Use the wheel wrench
hook that allows you to
pull the hoist cable
towards you, to assist
in reaching the
spare tire.