Hello all. I cant decide between running 37's or 35's. I drive a 2010 jk unlimited mountain edition. Will be purchasing a Rock Krawler 3.5 mid arm x-factor lift kit soon. What more would I have to do to run 37's compared to 35's. I do plan to regear in the near future, and already have the superchips... Unfortunatley I do have a D30 front axle. If I only found this forum BEFORE I bought my first Jeep, I would have known better... Thanks in advance for any help you can give me with this.... oh yeah, this is also my daily driver...

 

I recommend the 35's, over the heavier weight of going to 37's... in "most" cases it's not worth pushing the D30 over the edge.. The 1" extra clearance is not worth it imo. Make sure you strengthen that axle as well.
If you can get bye with 33's that would be even better, from a longevity standpoint.. But hey I understand.

 

As you have a 4dr Wrangler, I would suggest you get a set of 37" tires. As the matter of fact, you still need to get several things done to make a clear of 37".
First, 3.5" lift kit is not enough, I think at least 4" of suspension lift is needed, or even an additional body lift is in the list. Second, a set of larger number offset wheels are also needed. After the installation of the lift kits, if you still can't get enough flex rooms with 37", you may also consider a set of flat fenders; you can either custom your stock fenders or purchase an aftermarket product. Third, the front DN30 axle can handle the 37" on road, but for the off road plays, you definitely
need to get the front axle enhanced. For the regearing, 5.13 gears are okay with 37" tires.

 

The Rock Krawler kit will work fine with 37s if u do a little trimming (pinch seam, fenders-or flat fenders). I have seen people run this lift with 37s easily. However, a dana 30, heavier unlimited, and 37s, is a recipe for breaking stuff. I would stick with the 35s. The rock krawler lift on a 4 door with 35s will make ur jeep very capable. Even with 35s u will need to sleeve and gusset ur axle if u want it to last.

 

gusset and sleve your axel if you want to get any life. screw shafts as that will then make your weak point your r&p. this should hold up w/ no locker for a little while.
37's will fit this lift fine if you have flat flares, no snipping required.
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i will be doing the same set up in april.

 

I was in the exact same position as you
I bought the mountain edition clueless about jeeps and now I am wishing I would have known that when I bought mine
I went with the 35s because it's my dd and because of the Dana 30 and couldn't be happier

 

X3 I wanted 37's but with that Dana 30 I didn't wanna break anything so I just got me some 35x12.50x17 bfg km2

 

Well, i second everything that has been said here. With 3.5" lift, stick with 35's. You get better suspension travel with a little rub at full tuck, and the d30 will last longer.

That being said, from a strength standpoint, its all in how you wheel. If you wheel it like a 16 year old, and redline through everything, you would break stuff no matter what size tire you run. If you ease your way through things, and think about the line you are taking over a given obstacle, you may never break a thing. The d30 is weak hands down, so take it easy. I had a TJ sport for two years with 33" tires on it, and never once had to do any diff work. My buddy had a rubicon on stock tires, and blew the rear passenger side axle shaft on the same obstacle i paved the way over. All depends on how you drive it.

 

I will say I have 35s, but will try to goto 37 next time. And if I break something then I have an excuse to upgrade.

 

Thanks to all for their responses... I just LOVE the look of the 37's, but agree that running 35's would probably be the smarter decision... Although I have been known to not make the "smarter decision" in the past....LOL