BFG KO2 39x13.5xR17 on UD 44 Axles

[Renegade]

Upgrade to Chromoly shafts both front and rear for starters. Even 37s break or bend stock shafts.

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[Bombout800]

how are the axles holding up? What type of off-roading are you doing?

Very minimal off road for now. I live in south Mississippi and there's only a few places to go that aren't a complete waste of time. At least writhing a reasonable distance. Plenty of people running 39-40s with stock axles. It's either going to brake or its not. Just keep your wallet ready for when it does. Or keep spare parts.

 

[jenzeee]

Upgrade to Chromoly shafts both front and rear for starters. Even 37s break or bend stock shafts.

Sorry, that's bogus.

I am on 39s on stock axles and shaft. I have done quite a few very challenging trails since then, incl. the Rubicon trail with all obstacles. - No damages or problems yet.

And regarding 37s tires, the Rubicon stock setup easily handles 37s tires, - and I emphasize on "easily'. I don't know anybody who upgraded axles or so just because of 37s.

 

[Jeepnutz]

Upgrade to Chromoly shafts both front and rear for starters. Even 37s break or bend stock shafts.

If a guy doesn't wheel like a total moron stock axles are fine IMO. 31k miles on my 2019 JLU Rubi on 37" Nitto's running trails like the Rubicon, Fordyce Creek and Moab.

 

[jenzeee]

If a guy doesn't wheel like a total moron stock axles are fine IMO. 31k miles on my 2019 JLU Rubi on 37" Nitto's running trails like the Rubicon, Fordyce Creek and Moab.

A ”total moron” would also break those upgrades. - I agree, you’re totally fine to run 37s with stock axles & shafts. I ran 39s KM3 and now 39s KO2 on my Jeep with stock axles and shaft. No problems.

 

[FreedomFur]

I ended up pulling the trigger on 37s vs 39s.

 

[jenzeee]

I remember wibornz saying and showing twisted rear splines on his running 37's and LiteBrite also twisted the rear splines and bent the trussed rear on 38's. I guess it's all good until it isn't.
Myself, I have 19K on my stock axled JLR with 37's. Recently pulled the front axles and the splines looked excellent. I have not pulled the rear axles yet. Yes, I have rock crawled many of the popular trails west of the Rockies. Just none of the extreme rated trails. You will break stuff running 8,9,10 rated trails. I lived and wheeled in the PNW many years where wet rocks and mud are problematic. I do love dry rock crawling however.

It can have different reasons. As long as every modification (lift, arms, etc.) is installed properly, 37s are no problem for a JL Rubi. I started with 37s in the beginning, switched then to 39s and got now my second set of 39s. I have 75k miles and did quite a few hardcore trails with rock parks and so on. - No problems.

And, I did the Rubicon trail (rated 10) including all obstacles, plus plenty of other high rated trails (see photos, 1. “Soupbowl” at Rubicon Trail, 2. Barret Lake trail, 3. “The Squeeze” at Pinyon Mtn Rd). - Again, no problems.

If you’re in the LA area, feel free to stop by and inspect my ride!

 

[jenzeee]

Btw, got a new set of 39s KO2. - Drives like butter (almost like stock) compared to the heavier and more aggressive 39s KM3.

 

[Renegade]

Sorry, that's bogus.

I am on 39s on stock axles and shaft. I have done quite a few very challenging trails since then, incl. the Rubicon trail with all obstacles. - No damages or problems yet.

And regarding 37s tires, the Rubicon stock setup easily handles 37s tires, - and I emphasize on "easily'. I don't know anybody who upgraded axles or so just because of 37s.

Is it though? I bent a flange and also twisted the splines on the rear of mine. I’ve also broken 2 front u-joints, destroying an outer stub. So, I guess that’s bogus info…and I’m clearly a total moron.

 

[Some Random Guy]

Well, since my last post I’ve had 2 differential issues and a wheel bearing go. I don’t think it’s tire related, but a lot of members do, so pick your poison? I think its bad installs or parts because it’s pinion related setup or bearings both times.

 

[jenzeee]

Is it though? I bent a flange and also twisted the splines on the rear of mine. I’ve also broken 2 front u-joints, destroying an outer stub. So, I guess that’s bogus info…and I’m clearly a total moron.

What gives you proof/reason that it was caused by the "tires"?

 

[Renegade]

What gives you proof that it was caused by the "tires"?

Proof? Why do I need proof to state my opinion, and then post supporting information after being accused of posting “bogus” info and being called a “complete moron”? If I was putting 39s on mine, I would upgrade a bunch of stuff. Clearly, a lot of people wheel on 37s without breaking, but to pretend it doesn’t happen isn’t helping the OP with his original question. I didn’t even know mine was bent/twisted except for hearing a brake squeak. Turns out the flange was bent, and I discovered the splines twisted when I replaced the shaft. I’m not sure why you and Jeepnutz have taken issue with a recommendation to upgrade to Chromoly axle shafts if using 39” tires. It’s pertinent to the OP’s consideration.

 

[jenzeee]

Proof? Why do I need proof to state my opinion, and then post supporting information after being accused of posting “bogus” info and being called a “complete moron”? If I was putting 39s on mine, I would upgrade a bunch of stuff. Clearly, a lot of people wheel on 37s without breaking, but to pretend it doesn’t happen isn’t helping the OP with his original question. I didn’t even know mine was bent/twisted except for hearing a brake squeak. Turns out the flange was bent, and I discovered the splines twisted when I replaced the shaft. I’m not sure why you and Jeepnutz have taken issue with a recommendation to upgrade to Chromoly axle shafts if using 39” tires. It’s pertinent to the OP’s consideration.

First, I did not call you a "total moron". - @Jeepnutz used the term in his post on Dec 17th and I only quoted him. And I guess he was referring to people in generel. Look it up.

Second, I am just having a different option than yours due to my long-term experience with 39s tires, both KM3 and now KO2. I respect everyone's opinion, yours as well, but I have the choice to give my feedback to the forum and its users.

Coming to your point. I don't think you can blame it just on the tires, no matter if 37s or 39s. What @Jeepnutz was referring to ("morons") is, I believe, what you now describe e.g. as "wheeling without breaking" and so on. That being said, I guess we are on the same page regarding this point. But regarding your recommendation about upgrades (Shaft and axels) I have a different opinion and thus gave my input about my experience.

However, I agree I could have used a different term than "bogus" though.

 

[Jeepnutz]

Proof? Why do I need proof to state my opinion, and then post supporting information after being accused of posting “bogus” info and being called a “complete moron”? If I was putting 39s on mine, I would upgrade a bunch of stuff. Clearly, a lot of people wheel on 37s without breaking, but to pretend it doesn’t happen isn’t helping the OP with his original question. I didn’t even know mine was bent/twisted except for hearing a brake squeak. Turns out the flange was bent, and I discovered the splines twisted when I replaced the shaft. I’m not sure why you and Jeepnutz have taken issue with a recommendation to upgrade to Chromoly axle shafts if using 39” tires. It’s pertinent to the OP’s consideration.

Taken a issue? Now that's some funny shit right there.

 

[Jeepnutz]

Btw, got a new set of 39s KO2. - Drives like butter (almost like stock) compared to the heavier and more aggressive 39s KM3.

Looks sharp.. What width wheels and what's the mounted height? Couple friends running 39" KM3's swear they only measure 38" on 8.5 wheels.

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