I have found that different tire brands have different profiles for the same number values. I just retired a 120/70-18 Spitfire that gave me about .100" fender bracket clearance so I modded out my fender bracket as Keith did. Now I'm squeezing a 140/70-17 Avon on 17 x 4.25 rim in front. I can measure the clearance with a feeler gauge with my current setup. I may have to discreetly mill .030 thou off each of my lower fork tubes, if I find that the tire rubs. I've got this personal fetish thing for phat tires, front and back, as long as the bike stays safe and functional.
