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Discussion Starter #1
Hi everyone a newbie to the WJ world. I’ve been in the XJ/ MJ world for close to 20 years. I’ve seen some forums state you can run a 31/10.50 size tire with a 2 inch budget boost. Then you read further and then a 2 to 2.5 spring lift you can run up to a 30 inch tire. 3 inch lift up to a 30.5 inch tire. The tire options im looking at are. 1 st is I have a set of late JK Rubicon rims and found that 255/70/17’s are 31.06 inches tall. A 265/70/17 are 30.6 and 265/75/16 are 31.6 tall. I would like to stay with a 3 inch lift.



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I had the UpCountry Suspension and a 2" budget boost and ran 30.6" tires without any issues. I now have a 4" lift and run 32 x 10.50 tires and have minor rubbing issues that I am currently resolving. I tried some 1-1/4" wheel spacers and they (tires) would have definitely hit the fender. Took them off so my only trimming is the front bumper fascia.

Your biggest issue will be the Rubicon wheels as they have a 5" backset and the stock GC wheels have a 6-1/4" backset. You could wind up with rubbing issues that will most likely require fender trimming.
 

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A 255/75/17 is a 32 X 10 X 17 tire. There are online converters to help you with that.
As far as how much lift will clear XX" tire, that's a very tough question to answer because there are a lot of factors at play. Wheel offset, tire width, adjustable control arms, and I'm sure a few more. Another thing is, how much trimming are you willing to do? Sometimes the difference between 31's and 33's is some bumper trimming and the correct offset and width.
 

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Update. I did the IRO 3 inch lift. I put 2 inch bump stops on the rear. Made my own 3 inch spacers for the front. I put the Rubicon with the Cooper Discover AT/3 255/75/17. The rears were almost rubbing on the rear shocks. I put a 1 1/4 spacer on the rear. On the front I had a little bit of rub so I got another pair of 1 1/4 spacers for the front. It is worse. I took off the spacers in the front and did some minor trimming to the front facia. I’ve taken it on some local uneven Forrest roads. So far so good. I’ll disconnect the sway bar next time and flex it up and see what happens. I did find something out. The Cooper tire measure 31.9 per there catalogue. Goodyear, BFG show there 255/75/17 are 32.060 to 32.100 so maybe a .200 may help. Yea right.


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I also had a rubbing issue with my rear shocks. Instead of wheel spacers I installed some shock mount off sets from Rough Country. No more rubbing. You will wind up taking about 2" off the facia when you trim it. When you disconnect your sway bar find an area where you can flex your suspension and have someone watch where you rub while going over the obstacle. Trim accordingly. What did you set your caster and toe in at.
 

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Update. I did the IRO 3 inch lift. I put 2 inch bump stops on the rear. Made my own 3 inch spacers for the front. I put the Rubicon with the Cooper Discover AT/3 255/75/17. The rears were almost rubbing on the rear shocks. I put a 1 1/4 spacer on the rear. On the front I had a little bit of rub so I got another pair of 1 1/4 spacers for the front. It is worse. I took off the spacers in the front and did some minor trimming to the front facia. I’ve taken it on some local uneven Forrest roads. So far so good. I’ll disconnect the sway bar next time and flex it up and see what happens. I did find something out. The Cooper tire measure 31.9 per there catalogue. Goodyear, BFG show there 255/75/17 are 32.060 to 32.100 so maybe a .200 may help. Yea right.


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I haven’t set the caster yet. I don’t even know where it reads. I still have stock control arms. The 3 inch kit is bear bones basic. Toe is 1/16 tape using tape measurement on the tires. It tracks straight. A very slight amount of bump steer on really crappy roads. Very happy. It rides,handles better than any XJ I ever built except my 87.



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Do your self a favor and save up for adjustable upper and lower control arms all around. Caster should be around 4*. Increase your toe to 1/8" and that should help your bump steer. Have you measured to see if your front axle is centered? An adjustable track bar will allow you to recenter the axle and is a common replacement component for death wobble.
 

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Do your self a favor and save up for adjustable upper and lower control arms all around. Caster should be around 4*. Increase your toe to 1/8" and that should help your bump steer. Have you measured to see if your front axle is centered? An adjustable track bar will allow you to recenter the axle and is a common replacement component for death wobble.


My kit did come with adjustable track bar. No I haven’t check the centering yet. I just set it to what the IRO specs said in the instructions. I’ll put the WJ on the alignment rack this week and see where I’m at.


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