On a grippy track, the tires need to be cut pretty small.....certainly under 42mm max. to begin with, and sometimes even down around 40.5 at the rears. When the grip is really high, it can also be helpful to reduce the time that the sauce sits on the tires. At bigger races where there's a distinct black groove, I've found that wiping the sauce off pretty much right after applying it makes the car much smoother and easier to drive. By contrast, at my local track's club races, it is usually necessary to give the tires a good long soak (like 15 or even 20 minutes long) in order to keep the car from loosing grip towards the end of a run due to the tires drying out. Such is not the problem at big races, where figuring out how to deal with having too much grip is more often the challenge. Smaller tires and less sauce time does seem to help when the track gets grippy.