For your first question, a 190-50/17 is about the biggest you can go I think. However, if you wanna hit the curves stay with the stock size. For your second, no there isn't a limiter. The U.S. models have a different program than the Euro models. Look up "jumper mod" to get your bikes full potential. Search around and welcome to the forum. I apologize if I stepped on any senior member's toes.