when you go extreme the cars are not much cheeper, in baton rouge we have a 1200' velodrome to run on so a buddy and me built (at the time) a couple of the fastest 10th scale 4wd nitro cars around, we had a police radar mounted over the track and i busted 65 mph, the problem was gearing nobody made anything taller so we started with taller wheels/tires, the sustained high speeds were a new problem too id sling kevlar caps apart in a few hot laps and the belted radials handled good and made realistic screeching sounds would also blow up after about 5 hot laps, solid foam was the only thing light enough to not be flung off the rim. i got my 8th scale up to about 75 mph before we got burned out on racing, 65 with a 10th was way more impressive then 75 on a 8th