Any scale R/C tire would have too much "squish" IMO. And PBO, those spikes are a little extreme! I tried thinking of something that I could fill the tires with which would give them more or less the same firmness as air. I thought of spraying that hardening foam stuff, but I doubt I could do it uniformly.
In the end, I'll probably have to modify something like this:
http://www.lowes.com/ProductDisplay?...llow&cId=PDIO1