To answer your last question = not likely.
I am confused. Why would moving a wheel OUT cause it to interfere with the inner fender well?
Am I incorrect that a 4" backspacing will make the wheel stick farther OUT than a 5.5" backspacing? Would not the inner surface of the wheel be farther away from the inner fender well? I could see the problem where the wheels tucked into the fender well as on a sedan. This was a problem on Hondas that that were lowered which made them either roll the fender well edges out or actually stretch the fenders out to get the clearance needed.
As my Liberty sits now, with its 15 year old suspension sag, the entire top of the tire is still well below the wheel well arch.
Yes, the 4 inch backspacing will move the wheels further away from the center of the Jeep; the stance will be wider than stock. If the front wheels are straight there won't be any interference. But when the wheels are turned to go around a corner, then the problem shows up.
It's difficult to explain with just words - pictures would help. But do this...
Grab the end of a pencil or pen while holding it flat on your table. With the thumb and first finger on your other hand, "pivot" the pen back and forth along the table and observe the arc your thumb and finger trace along the table. Maybe even place a mark or other object on the table along the line the arc traces; imagine your thumb and finger represent your stock wheel and that the wheel clears the inner fender.
Now, move your thumb and finger to the end of the pen, opposite the end that's holding the pen; this represents the wheel with less backspace that moves the wheel further out away from the center of the Jeep. Move the pen back and forth and notice the new, wider arc described by your thumb and finger on the end of the pen. See how the wider arc 'hits' the imaginary inner wheel well? That's what happens when you decrease the backspace on new wheels compared to stock. The arc is widened and the tire will hit portions of the wheel well and/or suspension that it didn't hit before.
I'm sure there's a graphic somewhere out here on the inter web but I'm too lazy to look for it. The exercise above can be done with a high school geometry compass if you have one laying around. Trace an arc with the compass opened up an inch or so, then widen the arc to 1.5" - the idea is the same.
Hope this helps :shrug:
Bob