Yeah I think 12.7, 12.8 is the max clearance. Ive read conflicting info about 13.1 being true depending on rim size. I havent gotten a clear answer from Hoosier yet.Section width on QTP tire is listed at 13.10" and the 315 MT Rs have a section width of 12.7", and a lot of people have to pound down that rib for the latter. I am mounting and installing the 315s on my HC this weekend, and I already pounded down the rib for clearance. Judging by the QTP section width, you might very well have a clearance issue.