If you're trying to keep it as an all around machine then I'd suggest not cutting the foams. Star cutting the foams results in a ton of sidewall flex and if you were running around at any kind of speed the tire would roll in and cause the truck to flip.

If you still want to go with it then you may be able to boil the tires off. Do you know what your wheels are made of? If they're nylon then you should have no problem, if they're abs then I wouldn't suggest boiling them because they can easily melt and warp.