A while ago I cut up a tire found in the woods for moccasin soles. However, after removing it from the main tire and cutting off the bead, it came out too narrow for my foot. Today I finally found the energy to cut the tire into two foot-length pieces, bevel the edges, and glue them together with contact cement.
The bond feels very strong, enough so that I might do the other one. Unfortunately all the cracking will reduce the longevity, I figure, but at least they did not cost anything.