[Paul Gillespie]

I've had both, I prefer the 17" by far. If you lower the air pressure down to 25-27 lbs they feel just like 15". The 17"s have much better grip than the 15"s. They give you much better confidence in poor weather, on the track, and on the road in general. They're bunch more choices in 17 rubber than 15s. The only down side is they cost more.