the only thing with swapping to lower gears would be do they offer them and would i really need them? With the new engine and the 3.73's im doing great with the 35's, is 2inches bigger going to do that big of a difference, and if so, is it worth the extra money?

 

Idk with the new motor. Not to mention its subjective to the user. I'm running 35" with 4.10s and its bearable but I'm not sure I could tolerate them with 37s though. But then there are guys running them on 3.73s with the 3.8. I wouldn't think that could be desirable though. MattGT5 ran 37s on a '12 JKU with 4.10s and he said they were comparable to what I'm running performance wise. I say go for it. If its too slow, you can always change the gears later.

 

Went to 37's KM2's a few months back. Love the tire. They flex well on the rocks and seem good in snow. Was playing around in the white stuff and the traction was great. I went from 315/70/r17's which are around a 34.5 inch tire to the 37's. Best move i've made with the Rubicon and I averaged 16.4 mpg going from Huntington Beach to Big Bear today. 6sp manual with 4.10's. I have Gibson Headers, superchips flashpaq, MBRP exhaust and CAI. That stuff probably helps with the mileage a bit so im not sure how it would have done stock.

 

I guess the "good" thing about KM2's is they are the shortest and probably lightest 37" tire on the market. They are a solid inch shorter than a lot of other 37's when mounted. That's normally a bad thing, but I guess it may minimize the impact on a Jeep not really built to handle 37's.

 

He isn't saying to get new axles just to reinforce, sleeves and gussets. I would highly recommend this. I have a 12 with 4.10 gears on 37's and I WANT to regear, you will probably NEED to regear.

 

I have been tossing this idea around and have done some reading for 37s

regear- you most likely will want to, but you can probably push it if your waiting or plan on doing it near future

lift - I think the lowest you can go is 2.5 inch of lift with a 1 inch body lift. You have 4 so you should be good

fenders- even with 4 inch of lift, you may want to trim your fenders or get aftermarket flats for more room

trim the pinch seam

protection/axle - adding sleeves and gussets to a dana 30 should happen, probably even with a 44. also, replacing ball joints with a higher quality set would probably be necessary

tire carrier- if you plan on running a spare, don't forget about a setup to hold the weight

 

I just built a 2dr '12 JKR (really had built at a shop). Its on 37's, reinforced axles, armored flat fenders, 2.5" lift, 5.13 gears. It is a good set up. The must do is reinforced axle (these are D-44's), 5.13's, and flat fenders.

I'll post pics when it comes back from the painter.

Going bigger than 35" without having bigger parts is asking for breakage, like the axle shafts, knuckles, R/P, U's. I've been piecemealed before---its more expensive. If you want 37's then do the gears, get a bigger axle (did you say said had a D-30"'s? ). I don't mean to be discouraging. I love jeeps, and especially big jeeps. However, I've been on the side of having one thing break after the other, and I'm convinced the two biggies that make things break are size of rubber and weight (overall).

 

I have heard that there is a concern with 37s on D30 with 5.13 and the new 3.6......so if been told that 4.88 might be a better choice. Is this just a myth,, or is there some truth to this thought.....5.13 or 4.88 with 37s on a 12' or 13'?

 

Where in Oregon?

I found my 4.10s and 37s to be fine until I moved and now drive part way up a mountain hwy to my house.

If your at a lower elevation and not around a lot of hills, you might be able to get away without a regear.