Spare tire?? How do you lower the spare tire?? No manual with it?

Since the spare is mounted under the rear of the car, Its not easy...you have to assemble the long crank rod out of its two pieces, then feed the rod through the hole in the top of the rear bumper and lock it into the mechanism that holds the tire in place. Once the crank rod is locked in, lower the tire towards the ground. Once the tire is low enough, you can crawl under the car and release the tire from its mount. The hardest part is locking the crank rod into the spare tire mechanism through the hole in the bumper.

Remove retainer? Does it unscrew? Oh, after lowering, eh?
Uh, yeah, should, easy. You right.

Rotate the hoist shaft counterclockwise in order to lower the spare tire to the ground. Continue to rotate the shaft until the spare tire can be pulled out from under the vehicle and removed. If the spare tire does not lower to the ground, the secondary latch is engaged causing the tire not to lower.

If the secondary latch is engaged and the cable end is visible, perform the following procedure: 3.1. Tighten the cable by rotating the hoist shaft clockwise until you hear 2 clicks or feel it skip twice. You cannot overtighten the cable. 3.2. Loosen the cable by rotating the hoist shaft counterclockwise 3 or 4 turns. 3.3. If the spare tire can be lowered, repeat steps 1 and 2 to see if the spare tire can be removed. 3.4. If the spare tire cannot be lowered, rotate the hoist shaft counterclockwise until approximately 15 cm (6 in) of cable is exposed. 3.5. Raise and support the vehicle. 3.6. Place a transmission jack, or equivalent, under the spare tire. 3.7. Position the center of the transmission jack under the secondary latch release button at the center of the spare tire. Arrange the arms of the transmission jack so they will support the tire after it has been released. 3.8. Raise the jack until the spare tire stops moving upward and is firmly held in place, releasing the secondary latch. 3.9. Lower the tire. If the spare tire is hanging by the cable, rotate the hoist shaft counterclockwise until the tire is low enough to remove.

locate bolt or wing nut in centre of wheel and undo

CAN YOU PULL ON THE TIRE WHILE YOU LOWER IT. IT MIGHT BE GETTING CAUGTH UP IN THE CABLE HOUSING

U need the special wrench to lower the spare, there is no other way since the cable hoist is under the spare tire.

From the owner's manual for that model, see link below also, page 299 of the PDF has a nice picture.

Spare Tire Removal
Fit the jack handle extension over the drive nut. Use the
Lug Wrench to rotate the nut counter clockwise until the
spare is on the ground with enough slack in the cable to
allow to pull the tire out from under the vehicle.
CAUTION!
The winch mechanism is designed for use with the
jack extension tube only. Use of an air wrench or
other power tools is not recommended and can
damage the winch.
When the spare is clear, tilt the retainer at the end of the
cable and pull it through the center of the wheel.

http://www.jeep.com/en/owners/manuals/index.html?year=2006&nameplate=Grand%20Cherokee

dealer for the tool but it must be on vehicle like under the spare wheel or drivers seat

Ford's spares are held in place with a cable that's loosened by inserting the jack handle into the cable crank. it's located below the door sill of the rear door. Look for a hole that the jack handle can be inserted and turn counterclockwise. The tire should lower down for you.

Have someone pry down on the tire while turning...