Squatch

Im in my research stages of figuring out how im going to properly clear a 40-42" tire on a jkur. I have read in some build threads where they have stretched the rear anywhere from 1-3". How exactly are they accomplishing this? The jeeps in question usually have a teraflex or rock krawler lift kit. Are they just adjusting the arms out as far as they will go?


On a side note is that much stretch really needed on a jku? Im looking to clear a 41.5 X13.50 PBR and they are true to size. The rear looks to be only problem or would the front need adjusted out as well?

TheDirtman

The stretch is not really needed but you are going to need to do some serious trimming to fit those tires unless you are going with a really tall lift. It is easier to trim the rear sheet metal as there is really nothing in there but a piece of foam and some air. Stretching the rear with longer arms will make it look better centering the wheel in the wheel well. I would just go full custom long arm since you will be doing axles anyway and really dial in the geometry and not look at the "kits" out there.

Squatch

What exactly do you consider serious trimming? I come from the world of XJs so our thoughts on serious trimming is different than most JK owners that you would be saying that to. Just the edges of the fenders or totally enlarging the fenders? Plan to run a set of either metalcloak flares or poision spyder and trying to keep it around the 4" lift area after bumper and armor weight. I know what you mean about the "kits". I have pieced together my past two jeeps suspension from parts from various companies. There is always something missing in a kit or has that one subpar designed part.

Also talking about the stretching aspect. could a 2dr stretch kit be installed on rear of a 4dr. I mean suspension is the same isnt it other than the coil rates?

As far as axles i just dont know if i want to go tons or not. An occasional broken gear set or axle shaft with the rubi 44s is no big deal to me as long as it doesnt happen every trail ride plus it will be trailered to the trails.

DunnyBunny

I'd be more worried about a broken or bent axle, not shaft or gear. Although I wish I had to the money to just replace gears every other trail run. Lol.

TheDirtman

You might as well throw what you know about suspensions from a YJ out the window when compared to a JKU. You are talking 2x the weight on an armored JKU and 42" tires and the weight will equal bent or broken shafts no matter how easy you are on the skinny pedal. You are going to want 5.38 gears as well and it will still be a dog with those tires. Look for at least a 4:1 transfer case and 5:1 atlas would be better yet. 37" tires are about the biggest tires that really fit the JK wheel well when going bigger you are going to have to cut or go bigger then 4". There are a couple of threads of JKU running 42" tires you might want to do a search on.

Biginboca

OP you need to spend more time on here doing some reading. Most on here would feel it's pushing your luck running 37's on fully built (truss, gears, rcv shafts, gussets, aftermarket ball joints, etc) Rubi axles. Occasionally you run into someone pushing 38-40's and talking about all the things that broke.

Now you are taking about running a heavy 42" tire on stock axles is like 2 orders of magnitude outside of the 37's that are iffy, lol

Squatch

From talking to people who wheeled with 37s or larger they all said they held up fine after being sleeved and gusseted.

Yeah i know its totally different setup than the XJs im use to but practically same body length. Yeah guess i never really factored in the weight aspect. I see them on 40s now so often i figured they must be holding up well. Seems only threads i come across are either show and tell threads and a few builds. I did find one with exact tire setup im after on tons and he still has rub issues so may have to rethink my direction here. Only reason im after the taller tire is well im on 37s now on my XJ and need a larger tire to tackle the trails that my tire size keeps me from running.

Squatch

I get what your saying and ive read all that here and on other boards. But from most of my past experiences on forums alot of the omg your going to break if you dont do this is more of a keyboard hero thing and not their actual trail experiences. Just stuff they have read and continue to regurgitate it every chance they get. But i do understand there is a weakness there but i have wheeled with alot of JKU's over the years on 37+ tires and the level trails i run. Only issues ive seen are the stock shaft weaknesses front and rear. Then again those only broke during a near WOT assault. But like i said im still at a reasearch phase so finding all this out is good.

From most of my research since i started this thread though my WMS has got to increase to properly clear anything over a 38" tire at full stuff and full lock turn. Which there is no way around without going to a full width truck axle

951Rubi

You could just go the BlackOps4x4 route. Major trimming.

Sent from my iPhone using JK-Forum

TheDirtman

To run 42x13.5" tires I would recommend a 72" WMS with a 3.5-4" BS to maintain full turn and have room for axle rotation during articulation. Of course your suspension design and amount of travel you have will be a factor. With a conventional coil set up at 4" of lift you are not going to have much up travel without major cutting of the tub, but being a crawler that may not be an issue for you. I would really recommend you look at a double triangulated long arm with coil overs if you are looking to climb about anything.

You could also just by "Bane" it is already set up on 42" MTR's and ready to roll. I think it is still for sale. The first thing he did was buy 42" tires then the learning began on how to fit them.