I have used acetone for the race buggy wheels with great success. Works best with used tyres where you can cut the tyre off apart from each glued bead. But I have also used it just fine with whole tyres I want to re-use.
I got an airtight box to fill with some acetone to try and stop it all evaporating too quickly. I have also heard you can just use the vapour by holding the tyre above the acetone. Needs a bit longer but shouldn't ruin foams. With soaking them it took 1-2 days before I could get the tyre off normally. But if you try and it doesn't come off you just leave it another day. No big deal.
I am a mad RC loving lawn mower racing lunatic with a desire for over-powered RC's.