JKU 37's

gregaf3

Observer
So I am in the process of doing the suspension. I am on the fence if I want 35's or 37's. I have now had my JK for 6 years with a Teraflex coil leveling kit. I have had either 32" or 33" tires over the years. With 90k miles on my 2013 JKUR, I am planning on going with a lift kit that has control arms.

I currently have steel bumpers on both ends, Gobi stealth rack, and a rtt. I do have a M101 CDN2 that I plan on putting the tent on eventually.

Mostly used for trails and camping in the southwest.



Planned list

3.5 Clayton premium lift ( possibly their overland lift)
Bilstein 5100 shocks
Adam's 1310 driveshafts
New ball joints and tierod ends
Power Stop BBK (should be released in a few weeks)

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rho

Lost again
If you do 37's I'll suspect you'll need to look into doing gears, more trimming and beefing up the steering more than you have planned. Not sure how hard you use your truck, but my understanding is the limits of the front axle starts to show for moderate use with 35s, not sure how they'd fair under 37s with a lot of weight on the truck. I'd think 35's would get you everywhere you wanted to go with less chance of breaking stuff and easier to find replacements incase anything breaks or fails while out on a trip.

I'm curious to know how the BBK works out, I'm leaning towards going that way on my JKU at some point, but my poor jeep gets used like a prerunner on most of my trips.
 

gregaf3

Observer
Yeah. I have seen that Trail Region video a few times. Aside from the gears, I have everything covered.

I also have c gussets that I can install if I wanted to. Right now I can get some Cooper SST PRO 37x13.50r17 for $260 each. I could also change the lift to 4.5 for the same price as the 3.5. That was a motivating factor for going the 37 route.

Also, oddly enough many of the 35x12.50R17 tires that I find are E rated.


I am leaning more towards 35's for the pure fact that I have always gotten where I wanted to go. Sure my skid plates show it, but that is what they are for.

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jadmt

ignore button user
I have done the Rubicon Trail, Dusy Ershim and almost all the trails in Moab except for BFE. I have done, behind the rocks, Golden spike, Rose Garden hill etc and I ran 35's. never once did have issues. For me the pros of 37 did not outweigh the cons. I have a Rubicon as well with 4.10's and gearing with 35's are find with 37 I am certain I would want to regear. it also is not just the C's it is the tubes that bend. Copper ST Maxx in 315/70-17 are D rated KO2 come in the same size that are C rated. Nitto makes a cool 35x11.5-17 that is C rated. Kenda makes a new one in that size as well that is D rated and cheap.
 

thardin68

Active member
I have the Clayton Long Arm kit. I cant say enough about it. Amazing ride in the rough stuff.

I would not go to 37's wihout upgrading to a 44 on the front. I ended up with a PR44 Unlimited after messing up a few Dana 30's (heavily reinforced and upgraded). No issues since stepping up to the PR44.
 
Last edited:

Sand1235

Member
So I am in the process of doing the suspension. I am on the fence if I want 35's or 37's. I have now had my JK for 6 years with a Teraflex coil leveling kit. I have had either 32" or 33" tires over the years. With 90k miles on my 2013 JKUR, I am planning on going with a lift kit that has control arms.

I currently have steel bumpers on both ends, Gobi stealth rack, and a rtt. I do have a M101 CDN2 that I plan on putting the tent on eventually.

Mostly used for trails and camping in the southwest.



Planned list

3.5 Clayton premium lift ( possibly their overland lift)
Bilstein 5100 shocks
Adam's 1310 driveshafts
New ball joints and tierod ends
Power Stop BBK (should be released in a few weeks)

c5110de88aee105b73b02a2181d6edd5.jpg
8f4326daa317e586b719551b7b77b181.jpg
0702536d059d6150d553a7e93d28fc1b.jpg


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So my Jeep is a 12 JKU Sahara on 2.5" lift and 37s. 4.88 gears. I like the look, but from a daily driver status or overland status, I regret it. And they are the 37x13.5r17 Cooper STT Pros. Milage went down pretty good as well.

My brothers Jeep is a 12 JKU Rubicon on 3.5" lift and 4.10 gears. His Jeep rides great and gets decent gas milage still. He's on BFG KO2 315/70r17s. It goes anywhere and still is a great daily driver. I think it's about a perfect sized JKU.

One of my best friends has a stock JLU Rubicon on BFG KO2 35x12.5r18 and that Jeep is on par with my brother's in my opinion. They are both great Jeeps for Size/Capability/Daily driver in my opinion.

I regret the 37s on mine a little bit.
 

spartancrating1

New member
Bro get 37's. You will look at those 35's every day and wish you went bigger. Just picked up the 37" Coopers and they are legit. Posted are pics of my Jeep with the 35's and now with 37's. The four door Jeep stance with 37's is perfect.
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Inline6

Adventurer
For what its worth. I run 37s with Synergy 1" springs on my JKU. I have a fairly light rig and they netted me more like 3" or more of lift. I tried their 3" springs and was way to tall IMHO and YMMV.
 

Yarjammer

Wellreadneck
With 90k miles in the seat of your JKU, you know what its capable of and where it's shortcomings are. If you wheel smart and don't have anything to prove to your trailmates you should have no hardware breakage issues running 37s that shouldn't happen with a smaller tire.

I'd focus less on 35" vs 37" class tires and look at the actual tires in both sizes since the variations in real world dimensions are enough that the lines are blurred a bit. Another consideration is tire weight, if you're set on M/Ts they're usually going to be heavier and appear bigger than an A/T of the same size. I've parked next to quite a few JKUs with fresh 35" M/Ts that make my 37" KO2s look the same size and in one case smaller. Beyond the tires, consider what the extra height is going to mean for your daily and camping routines; things like getting in and out if you're of shorter stature, parking garage clearances and roof rack/RTT access (when I went to a 4" lift w/ 37s it got a whole lot tougher to put my RTT annex on and zip the cover).

For me 37s are an aesthetic choice; I had 35s and just didn't like how they looked on a four door. 35s performed well and did everything I asked of them otherwise. Will I do 37s again, absolutely but I'll go with something slightly more aggressive that handles deeper snow better. My only regret is not being able to afford the changes necessary to go to 38/40" tires. One benefit I didn't think about until after I did it was I don't need jacks or stands for maintenance unless removing tires.
Below is my 2012 JKU Sport w/ 37" KO2s, 4.56 gears, OME 4" lift, front & rear air-lockers.
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spartancrating1

New member
Great points. I'm wondering how my annex is going work out with the 37's. It was already high with the 35's. Im running 3.5 Metalcloak game changer w/ 6 packs, Gobi Stealth, and 37" Cooper STT Pros on 17" Armories
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Blue Baby Sound

A guy with a Jeep
IMO the STT run really small to their stated size, we run them in 37x12.5x17 on our '18 and 40x13.5x17 on our '14. If I remember correctly a 37" really only measures about 35 3/4" depending on your Jeep's weight and PSI.
If you go with the 37" Cooper I'd suggest the 12.5" wide instead of the 13.5". 13.5" will require less backspace therefore changing the scrub radius even more, increasing wear/tear on ball joints and unit bearings.

Tires are a tough choice. Good luck!

2014 JKUR and 2018 JK
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On my 08. Jkur I ran 315 70 17. With no gearing change. Now keep in mind that is the old 3,8 underpowered for sure. However it was bullet proof oh and I had OME 4 inch heavy duty springs to handle that insanely heavy front bumper and winch. No where did I go where I was too short tire wise. I am running 315 70 17 on my new jlur too If you go 37s be prepared to spend a bunch more. Gearing Suspension axels all will require up grades also higher. Gears equal. Less metal. Equal higher chance of breakage. Unless you really spend some $$$$. The question is do you want just rock crawl hard trails or overland. You can do both with either set up although. One way is more slanted towards Rx the other overland. As for my 08 Rubi. Had 175000 on that wimpy 3,8. And was still running strong when I sold it. For 11500.
 

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