I cut a sidewall notch out of Bro2's old 300 Metzeler to check the sidewall ridge thickness and found that there was 7/16" of rubber over the cord. We shaved off some of the sidewall ridge untill it was about a 3/16" wide flat area with a belt sander. The bike was on the lift and center jack running in 1st gear. This gave us plenty of gap 1/8" or so. I have no problem doing this. We run our belts a bit looser so wheel bearings and others to survive longer and wanted the rear tire correctly aligned to reduce tire wear. No hard belt rubbing before but none at all now.