I buy myself some Black ABS pipe in the right ID (inner diameter) from McMaster Carr and turn them on my lathe. I chuck in the pipe and cut pieces off the width of the rims I'll be using. then once i have a few i chuck each one back in the lathe so i can turn out a little channel for the out side lip of the rim to sit in. so it actually looks like a tire. then after that i round off the corners a little with a hand file while they are still turning on the lathe. they come out looking really nice, but that changes real fast once they get on the car. it scratches up very quickly. just a tip - i use a little bit of RTV (silicone Sealant) between the rim and the ABS tire to prevent slippage.