Rim Choice with Dr. Diff's 13" Brakes

Are those 14x8 or 14x7? If they’re 8’s the 275’s will be over a 1/2” further inboard on 18x9 +35’s. Heck even if they’re 14x7’s the 275’s will be about 1/8” further inboard.
They are 14x7's. I remembered the backspace wrong though, it's 4" not 4.5.