 The bottom groove of the racetrack, there's nothing on it. It's just the raw, light gray concrete. Up one lane, that's where the traction compound is, the resin. Above that, we see the rubber that was laid down in about two lanes from yesterday's Xfinity Series race. And depending on how brave you feel or how out of shape you are, you may find yourself all the way to the top of this 50 feet of width.