If you just can't find what you want then I suggest the following.
Buy something like the bicycle rack linked below, which is rated to 120 lbs.
bike rack linkThen cut the end off at the curve so that it is just a post sticking straight up. Get some 1/4" plate and drill/bolt up something in the shape of an H (or just a big square) so that you can bolt the wheel to it and it will hold solid. Finish by getting a thick piece of pipe that you can slip inside the bike rack post and bolt it in. Then attach the H to the piece sticking up with a couple bolts.
Alternately, you could buy the rack and ask a local shop to weld up something that will hold the wheel on. Figure the shop will charge a couple hours labor and materials. Total cost with the rack would probably be around $400, but you now have exactly what you wanted. They might even be able to make the wheel mount rotate so its easier to mount the tire back on there.
Jose
