When I bought my '85 one year ago with 37K on the clock I assumed it came with a spare tire. I know my '86 has one because I looked at it one time. I guess I better look down "between the tail pipes" for the dirty thing and be sure it is really there!
Just checked mine today. 5lbs. A tad low. Filled it up. Also found a ton of dirt stored in there and what looked like a retired birds nest! Well after cleaning the whole thing up I now have a working spare and shaved a few pounds off the car...
:L By now I would have thought that someone would have thought that by utilizing an extension (like those used for duallies) from the air valve on the tire, then running that out through the rear of the carrier and tied-off with a plastic tie. It will then be in a position where it can be accessed much easier, and therefore the spare tire air pressure can be checked more often. That's what I did.
I got mine through Griot's Garage but you can probably find it cheaper somewhere else.