I have a mini tubbed bu with frame notch. How would i measure inorder to fit the biggest tire with what size rim. Curently has a 15x10 prostar, dont remem backspacing with a 28x11.5 et street. I have about 2" for room to the inside and about an inch to the fender lip, up words it seems i can fit atleast a 30" tire, maybe more. Any help would be great.