Agreed. After all the reading I did before buying, I was positive that I wouldn't have any rubbing with 265s. At least it's a fairly easy fix, I don't think I'll have to trim the fender but definitely move the liner forward. It only catches in reverse, but not at all going forward.
It could be a combination of those things, actually. Bigger tires are always going to be harder to balance, especially the more sidewall there is. I worked at Discount back in the day(03/04), and always hated balancing the 38" tires on like 15" wheels. It can take a lot of time, and some guys wouldn't have the patience to get it perfectly balance, so if it's "close enough" they'd send it out. Most of the time, though, it was either the wheel or tire being the issue that kept it from ever balancing on the machine.