I have a 2.5" coil lift with 3/4" spacer in the front. I also have 1.5" spider wheel spacers. I'm running 305/70r18 xtreme mud terrain tires on stock sahara 18" wheels. When I disconnect I rub the sway bar real bad. I put probably 3/8" of spacers on steering stop, still rubs at full stuff. My friend has a rubicon unlimited with 3.5" rubicon express lift, 35's on Procomp wheels with 4 3/4" backspacing and rubs his sway bar also. So if you disconnect and wheel your rig pretty hard what back spacing is required? I'm thinking I would like to get wheels with a 4" back spacing, I just don't think 4.5" is truly enough or is it? I can't find any inexpensive aluminum wheels with 4" of backspacing. I'm starting to think real hard about going to a 15" wheel, so I can get 4" or less of backspacing any thoughts on this. I'm not sold on the whole old school 15" wheel thing. Any of you that have made the leap to 15" wheels with 35's or larger please chime in. Considering 36x13.50 iroks. Wondering if I could mount them on a 8" wide wheel? If I mount them on a 15x10 wheel they are going to stick out way past the fenders. Maybe mudflap time.

 

Backspace is the distance from the mounting surface of the wheel and the back edge of the wheel. (Mounting surface is the surface of the wheel that touches the hub of the vehicle.) Backspace is always expressed in inches. The smaller the backspace is the deeper the wheel lip will be which means the wheel will stick out more on the vehicle.

The 15" rim won't clear the brakes or rear swaybar links.
A 36x13.5 on a 8" wide rim will buldge and rub on the frame behind the front wheel at full turn or stuff in the top of the fender at full flex with your lift.
That is a heavy tire to run on a spacer... just my

 

There are plenty of people running 15" wheels with 3.75 backspacing that don't have any problems. Others may have to perform some minor grinding on the brake calipers.