Sorry, posted in wrong forum so I removed my original post and replaced it with the 'whoops'.
The main track surface is a 1/2 inch solid piece of wood (particle board). Not particle board in the traditional sense, the wood sheet is made up of very tiny, sawdust type-sized pieces of wood, and glue. The banked ramp leading to and from the bridge are a solid piece of cardboard, but that is the only piece of cardboard used on the track as a driving surface.

** RE-RE-EDIT
Here's an image of our first track in its beginning stages. Hopefully soon, you be able to see more and read more when we release our website, but for now, here's what our track looked like a few months ago.


We drive the Bit-Char-G cars on it.
Normal, stock tires work fine. Of course a 3.0 motor and high-torque gears coupled with 'hard' tires (slicks), you could produce some doughnuts.