13.5 with Sintered rotor people in our area are going up 5-8 teeth on the pinion from brushed motors. Right now I'm running a 46/90 and still not geared as high as some. If I were to start buying them now I would get 45, 46, and 47 pinions with 100 and 94 spurs. Shouldn't have any gear mesh issues with those.
Running rubber tire on carpet.