scottin-
if your the same size as VXkat then theres no way that your tires will hit when your going straight, they may slightly rub when turning, but that just takes a little cladding trim (seriously like 2inchx2inch triangle thingy)...
and if its rubbing on the frame, then 1. dont turn it all the way sharp.... 2. change the bump so your VX physically cant turn that sharp