Will a 18 80/140 fit ok on my xr650r? it is wider but lower profile than the 100/110 that is on it now. reason I am asking is m neighbor bought one for me and is like new. the one that is on it is a dunlop 100/110 but the knobs are rounded and the rear on mud and hardpack is all over the place. will the 140 be too wide? will the 80 profile be too small and what gearing changes will it make? smaller tire should give less top end speed but a bit more torque am I correct?