Ok, while trying to figure out wheel options, I knew that the wheel and tire combination needed to stick into the wheel well (toward the center of the vehicle) somewhat similarly to OEM for clearances when the front wheels and tires where turned (to full lock one direction or another).
Personally, I decided I wanted to go from the 17" stock OEM wheels down to 16" so for the any given O.D. of tire, I'd have more sidewall height. I wanted this for 2 reasons: for increased protection of the wheel rim and to help the tires visually appear larger than they actually were.
The OEM 17" wheels (on my Limited) measure 17" x 7.5" with 5.5" of backspacing. I tried to get some technical dimensional info out of Jeep sources to validate published data for this wheel, but was unsuccessful. So, given my measurements of the OEM wheel, I created a quick little comparison table below to help me evaluate the amount the face of the wheel would stick further out from the vehicle versus stock:
In this table, I had highlighted in green the 16"x8" wheel options that had 1-1/8" or less further "stick-out" and similarly for some of the few 17"x8" wheels I evaluated I highlighted in blue. The 1-1/8" further stick-out was my speculation of the maximum allowable to likely work. With this info, I did a quick little sketch and dimensional study of the wheels I chose (Ultrawheel 174 Nomad) and 245/75R16 tires (30.5" nominal OD x 9.6" nominal width) to check turning radius and confirmed they should barely clear. Seeing the real-world results versus my quick evaluations, if someone wanted absolutely no rub at all (say on a lifted KK without the pinch seam modification and not under compression), then I would recommend a 5" to 5.5" backspacing on an 8" wide wheel rim. Of course, a tire with less aggressive tread knobs than my MT/Rs would probably also help. I personally chose my wheel over those that offered higher backspacing (for a 16" wheel) due to personal preferences regarding wheel styling and appearance.
As for tires, I had my local Goodyear dealer bring in 3 sizes of the MT/Rs:
1. 245/75R16 (30.5" nominal OD x 9.6" nominal width) -- I knew these would fit, but wanted to evaluate some larger OD options
2. 235/85R16 (31.7' nominal OD x 9.3" nominal width)
3. 265/75R16 (31.6" nominal OD x 10.4" nominal width)
For reference, my OEM tires were 235/65R17 (29.0" nominal OD x 9.3" nominal width).
We test fit the 235/85R16 first. Given my 4.875" backspacing on my 8" wheel (so 1.125" further stick-out), there was too much rubbing/interference at full lock on the front for my comfort level. I speculate another 1/2" or more of backspace would have likely provided clearance for this tire within the front wheel well when turning from full lock to full lock. Given this, I chose to stay with the wheels I selected and the 245/75R16's. Yes, I chose wheel styling over maximum tire size. I was also somewhat concerned about going to a tire > 31.5" nominal OD and having that much more loss of effective power since I don't plan to regear until I install lockers and that won't be until probably spring 2010. Since the 235/85R16s rubbed, we didn't even test fit the 265/75R16s which, since they're wider, would've had only more interference/rubbing since they were all mounted to the same/new wheels.
For more info on wheels and tires, see
this section on LOST. Also here's some
wheel technical info,
definitions and
other info as reference.
Hope this helps.
_________________
2009 KK Limited 4x4Jeep Green/partially dechromed/Sunroof/OEM Skids/
Gray Leather/uConnect GPS-Nav/DVD Head Rests/
MtnLuvr's Off-Road Front Winch Bumper, Heavy Duty Rock Sliders, Heavy Duty Off-Road Rear Bumper/JBA 4" AaS Lift w/UCAs/16x8's w/ 245/75R16 GY MT/Rs
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