The height of the tire (aspect ratio 70 or 80 (80 being taller)) isn't the problem but the width slowed me down a bit. The width change of the tread, from 120 to 140mm is about 3/8 ths of an inch (10mm) wider on each side. On the exhaust side, the clearance is over 25 mm at its narrowest and just under 20 mm on the drive side (left side of the tire). I ran my hands around the tire, removed the inner fender and checked it every way I could ... I finally bought the Avon - but won't have a chance to mount it for at least another week.
I'll get some before, after and comparison photos when I have it done. My mechanic has done this step up on other types of bikes ... he said each bike has some variations, but he felt that it 'should' fit. My fingers are crossed.
Dion