I had kdw2s and i used to go around the water and do a quick like 2 sec burnout just to get them clean. heating street tires never helped me out at all at the track.
you should drive around the water box when not using skinnies up front anyways...you'll track water onto the track and could make it dangerous for you or someone else. If you need water for your rears back into it...otherwise a dry burnout will clean up your street tires.
no water, 4sec burn out. just enough to get them warm, but not too long or they start to get bad. its not science, but just a quick spin isnt going to help after sitting and letting the tires get cool in the lanes