I've been researching this quite a bit. I plan on putting WK2 rims on my 2005 WK. I've seen a few pictures of 20's on a WK but none of 18's. What are yalls opinions on which would look better? I'd appreciate pics, if you've done it, for both size rims!
I was looking to do this too. A google search turned up several threads in Jeep Garage that turned me away from attempting it.
WK2 wheels have different offset than WK wheels. The wheel is moved in toward the suspension by about 1/2" and will interfere as you found out. You can use them but you need to use wheel spacers front & rear and longer wheel studs. Four spacers run about $300 plus cost of the wheels. Also, there are some threads about the lug nuts being different. The WK wheel lugs have a taper that holds the wheel. The WK2 lugs have a taper and a ridge that engages the wheel.
I felt the effort, cost and mods required to mount the WK2 wheels wasn't worth it. I'm going to go with STR reps when I get the cash together.
personally id go the 18s. i currently have the sahara 18s off a JK and they clear the calipers perfect and really are proportionatel with the WK. the 20s wont be that proportionate i feel, unless theyre the srts. im not looking forward to going back to a 17, because the 18s provide ample clearance for the calipers and you know you wont rub them where as the stock 17s hug the hell out of the caliper