larrydale,
If they are the ones sold by TBird suppliers (check Hill's Thunderbird Center online catalogue, page 20) they are easy to remove and install when you've done it once or twice.
Grab the center ring with both hands and pull the entire cover straight out. It will pop out about 3 inches from the wheel and lock in that position. Reach in behind it to one of the steel clips (should be 5 on each wheel) and unclip it from the back of the wheel cover. Do this at each clip and the cover is free.
To install the cover is the reverse, doing each clip one at a time. I find that every so often the wire spokes may be in the way when clipping the cover on, so I simply rotate the entire cover slightly to get the clip to find a spot away from the wires to lock onto the cover. Once all of the clips are attached to the cover, push the cover towards the wheel to lock it into place.
Hint: I remove my covers during winter storage but leave all of the clips on the wheel. To ensure that I don't lose any of them, I tie a heavy cord around the hooked ends of each clip and then tie it altogether. This ensures that the clips all stay in place if I have to move the car. Good Luck!
