How much bigger of a tire would you guess that you go with before they would rub when turned?
With NO trimming? I couldn't definitely say, but i would guess 40's with no trimming. Since I see you're doing a SAS too, i would suggest 56" front springs if you wanted to run bigger with no trimming. It would allow you to move the axle forward more, then you could build a bumper to accommodate the clearance up front.
This picture best represents the wheel well opening, even though im a little embarrased i left all that IFS junk on the frame. Those are 36x13.5 iroks on 16x10 inch wheels with 3.5'" (I think, maybe 4") backspacing.
It shows just how much room is there.














