On my car.... With a stock width rear end, 7" wheels with a 4-1/4" backspace is dead centered in the usable wheel space. I'm currently running 15x8's with 4-1/2" backspace, which moves the wheel 1/4" outboard from centered. A 255/60 should fit, but a 275 will be hit & miss. I see that sputnik is running them, and I'm very interested in the pictures he posted up. I think from car to car, though. results may vary with 275's.