GMC Envoy Owner's Manual page 426

CAUTION:
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The underbody-mounted spare tire needs to be
stored with the valve stem pointing up. If the
spare tire is stored with the valve stem
pointing downward, its secondary latch won't
work properly and the spare tire could loosen
and suddenly fall from your vehicle. If this
happened when your vehicle was being driven,
the tire might contact a person or another
vehicle, causing injury and, of course, damage
to itself as well. Be sure the
underbody-mounted spare tire is stored with
its valve stem pointing up.
Notice: An aluminum wheel with a flat tire should
always be stored under the vehicle with the
hoist. However, storing it that way for an extended
period could damage the wheel. To avoid this,
always stow the wheel properly with the valve stem
pointing up and have the wheel repaired as soon
as possible.
Follow this diagram to store the underbody-mounted
spare.
1. Put the tire on the ground at the rear of the vehicle,
with the valve stem pointed up and to the rear.
2. Pull the retainer (D) through the wheel.
3. Put the socket end of the extension (C), on an
45 degree angle downward, through the hole in
the rear bumper and into the hoist shaft (B).
4. Raise the tire fully against the underside of the
vehicle. Continue turning the wheel wrench (A)
clockwise until you hear two clicks or feel it
skip twice. This indicates that the tire is secure and
the cable is tight. The spare tire hoist cannot be
overtightened.
A. Wheel Wrench
B. Hoist Shaft
C. Extension(s)
D. Retainer
E. Spare or Flat Tire
(Valve Stem
Pointed Up)
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