As others have said, foam will work outside if you use the right compound. Like any tyre, foam or rubber, if its too soft for the surface you're racing on it'll burn up in no time.
Ive raced nitro foam on an electric sedan before, and even without additive it worked OK. I could be convinced to try it if the rules allowed, but in general I prefer rubber tyres for outdoors.
Sorex 28 are a happy medium when the track temperature is up, pretty good grip and they'll last well, expecially in stock.