It’s definitely the offset, which is why I thought a small spacer would solve it. The Nittos I currently have on the truck are 295/55/20, which are actually 12.17 inches wide. I think if they were actually 11.6 they Probably would not rub. I am over 200,000 on vehicle, but.....I had what I was told was stock Z71 Tahoe measurements before I added the blocks and spacers. It was dead on. On stock tires I was 39 inches ground to bottom of fender, with nittos, I’m a little over 41.