I have a 2007 JK Unlimited Sport 2.8 CRD Autom now with 245/75R16 under, and am planning to change them to 255/85R16 or similar 33".
Would like to know if these will fit in without any lift kit installed or not ?
Doing also some rough offroad driving occasionally. Will they rub during x-hang situations when suspension stretched to its limits ?

 

I am no expert, so hopefully others will chime in.

My 33's on 15" w/4.5" backspace do not rub at all. It is close though and would on a trail if turning hard and loading the front. This weekend I will tackle my FT BB before I take it off road again.

 

You will rub with flexing. You also will need less backspacing on your wheels or wheel spacers if you are running wider tires. Any small amount of lift should suffice. The stock Rubicons come with 32's.

 

No lift needed. You will rub at full flex but its only in the plastic fender, no metal involved (that is if you run 33x12.5)

 

I've got 275/70/18 Toyo Mt's on my JK with a 2" BB I don't think I would want to go without the lift. There would be rubbing as I rub with lift now (minimal) but physically I think I need more lift just to look right (too much tire in the wheel wells, it's the cool factor)!