The 200 mm conversion is to make the tc3 a "rally" car. It handles great at 190. 200 mm is not legal at races for electric. Also if you broke you would have to replace with the harder to find 200 mm parts. I think associated discontinued that kit so you might check it out before you try it.
i just bought 4 hpi foam tires on black rims that comes with spacers to push out your tires to fill out the 200mm body on an electric car. they are just 6 sided peices of plastic really thin that go in the rim. then the nut goes in the rim behind the spacer.