I went with a 140 on the back and a 100 on the front of my 500, brand new Shinkos, rode 1120 miles from Portland to San Diego in 19 hrs, then came back stopping in Winters and Sacramento to visit family for a total fof about 2280 miles, mounted myself, unbalanced but lined up the dot with the air valve, no vibration below 85mph, not much above that, but thats about when my paranoia kicks in, so I didn't go much beyond that.3 or 4 hundred miles since then and these tires hardly look worn.