It's hard to tell, but as long as it is smooth enough, you can race on it. I race every weekend on a flat asphault surface. We use foam bsr tires usually purples all the way around, and sometimes we get creative and put a double purple on the right front and a double pink on the left rear. Hope this helps.
The smoothness is good, we've had a couple of karts on it,
It will be a kart "plus" track once its finished, This fall, we'll add the other
lanes, a total of 34 feet wide. all and all there will be 3 tracks total.
Send me a PM and a email, and I'll get you some info on the track.
I just got out of the hospital,with a hip fracture, been moving a little slow this week, track is just setting there. waiting on someone to use it.