Yea I use 20's..I think with that tire size a 15 would be too big

thanks

 

Along with the 14 tooth I also run 22" tires (I still end up bouncing the skid plate of of stuff). There is a blaster speed calculator around using blaster drive ratios and engine rpm, in a perfect world with no wind, rider wieght and other outside varibles my blaster could hit around 66mph.

Even with my blaster being wider and longer then stock, the blaster gets awfully twitchy when nearing top speed.

I would also be very carefull about putting a 15 tooth front sprocket on, a 14 tooth sits real close to the engine case. If anything run a 14 and drop some teeth off the rear sprocket.