Acetone is a fairly nasty chemical that u can buy at any home supply store. Be careful of the fumes inside the house or around pets/people. Put a screen or something inside a jar/container [w/ a lid] and put the tires on top of the screen, w/ a bit of acetone at the bottom. Just a dab will do ya. Fumes will loosen the glue, no need to submerge the tires. Leave for a few hours, peel old tires and foams, throw them away and reuse the wheels.
I know Tamiya will melt, and HPI won't. Don't know how u tell for other brands. Just keep your eyes open for info someplace, or u could always experiment. I saw a listing of brands/compounds somewhere, but cannot remember where. I will post if I can find it today. Hope that helps. Cheers.