i use wood burls for knife handles all the time.(english briorwood,splatted birch etc. problem with burls, the wood likes to seperate.
all my burls are actually stablized (epoxy forced into the wood under presure) so when your cutting/shaping it it smells and works like a solid block of plastic.
i wonder if those wheels are being stablized? i doubt it (cause there would be no need for any sort of protective finish/powder coat)the epoxy in the wood buff's right up.
i'd be worried about those things blowing apart at speeds. a stablished wood rim on the other hand, would probably last a lifetime.