I have a 84 CJ7 with wide-trac axles, d30/amc20. What kind of backspacing would I need to run a 33x13.50x15 ltb tire, I'm looking at 15x10 cragars with 4" bs, but would I need less than 4 to run these tires without worrying about rubbing the inner wall? I'm going to upgrade to 1 piece axles, would 4" bs be enough or should I get 3.75" bs? I'm curious if anyone out there is running a d30/amc20 with these tires?

1/4 inch isn't gonna make a shit one way or the other. I would think you'd be ok with the 4"ers since you are only using a 33" tire. Any larger diameter thought and I think you'll rub some. Of the two, I'd buy the wheels with the best price.
Travis..

Just wasn't sure how much more the ltbs stick out past the rim when aired down.