This was mine last year - VERY Fast, but if you notice the rubber wheels are out too wide. If I would have had a round cap nut as a hubcap, I could have done better when I did hit the sides (after too many beers trying to line it up straight) . I may run this exact same car - BUT shave the skateboard wheel off to curve it inward - lower the surface contact but eliminate the side areas to skip off the boards with a cap nut. Skateboard and inline wheels and bearings are very good - its a matter of mounting them straight.
BY THE WAY - there will be a "Best of Show" winner as well with trophy. Not a winner per se' but the best design overall. I'd love to see a speedster body over top of a valve cover