My bike is stretched 6 inches and I was running a 50. Went to a 55 three months ago and instantly I could tell a HUGE difference in the way it handled. I mean I was able to whip this bike like never before. I love how it feels, but hate how it looks. I am chromed out and the back wheel is ugly to me now. I am putting a new 50 on this week. I live in DFW so its mostly highway for me anyway.