GMC 1999 Envoy Owner's Manual page 239

Before you can lower the spare tire, you must remove
the access hole cover on the passenger's side of the rear
bumper. Insert your index finger into the indentation
near the lamp and pull to remove the cover.
To remove the spare, insert the chisel end of the wheel
wrench, on an angle, into the hole in the rear bumper. Be
sure the chisel end of the wheel wrench connects into
the hoist shaft.
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