I want bigger tires... but

mgroeger

TJ Enthusiast
Joined
Aug 24, 2018
Messages
807
Location
Hurricane, UT
My apologies as I know somewhere on here I asked this question on a thread but I can't find where it is, hence this thread.

2004 LJ automatic.
I have Dana 44s front and rear with 4.88 gears and I am running 33s x12.5 on 15" rims
I was told DON'T go to 35s unless I go to 5.38 gears because of the OD in this transmission and how it LOVES to stay in OD. I have experienced this even with the 33s where I will kick the OD off when getting on highway ramps or up long hills annoying but still only a first world problem.

I met a guy with a 2003 TJ who is running Dana 44 in the rear and I forget what up front (I think 44 as well). He has and automatic and 3.73 gears and is running 35s with no problem at all, he said it doesn't struggle on or off road. What's the deal? Is the tranny different between '03 and '04?
 
Not sure when the 42rle came about but I have the 3 speed auto in my 2000 with 35's on 3.07 gears. It's fine on the trails when I'm in 4 low and isn't that bad on the highway either. That being said it's not my daily driver and I'm swapping to 4.56 in the near future. I have heard other members on the forum like the older 3 speed auto better than the 42rle, but I'm not sure for what reason.
 
My apologies as I know somewhere on here I asked this question on a thread but I can't find where it is, hence this thread.

2004 LJ automatic.
I have Dana 44s front and rear with 4.88 gears and I am running 33s x12.5 on 15" rims
I was told DON'T go to 35s unless I go to 5.38 gears because of the OD in this transmission and how it LOVES to stay in OD. I have experienced this even with the 33s where I will kick the OD off when getting on highway ramps or up long hills annoying but still only a first world problem.

I met a guy with a 2003 TJ who is running Dana 44 in the rear and I forget what up front (I think 44 as well). He has and automatic and 3.73 gears and is running 35s with no problem at all, he said it doesn't struggle on or off road. What's the deal? Is the tranny different between '03 and '04?

There was a transition in the Jeep tj automatics when they switched to the 42rle (what’s in mine) in 2003. Now which transmission your friend has could change his experience. Attached is some info regarding the difference and years. You can see in the pictures the final ratios (OD) which is what most people regear for when they do highway driving on bigger tires.
49DE559C-CE7B-4987-8911-5E4E7419BBB8.jpeg
86C107FF-3FEF-45BA-89DF-21065271460C.jpeg

A 1:1 overdrive isn’t bad at all with his setup (i’d still prefer lower gears for torque at highway speed) but as you can see the 42rle (newer tj trans) is a dog with 0.69 OD. When you add in the considerable mass of 35” tires and any other weight you’re carrying anything higher than 5.38 gears will lug the engine unless you’re doing 75+ mph. You can get away with 5.13 but the jump is just nicer.
 
....

I met a guy with a 2003 TJ who is running Dana 44 in the rear and I forget what up front (I think 44 as well). He has and automatic and 3.73 gears and is running 35s with no problem at all, he said it doesn't struggle on or off road. What's the deal? Is the tranny different between '03 and '04?

Same transmission. Its a Jeep thing. They are slow, perform poorly, ride like crap. With this assumption firmly in place, I'm sure your guy thinks his lousy gearing is fine.
 
Last edited:
  • Like
Reactions: psrivats
I met a guy with a 2003 TJ who is running Dana 44 in the rear and I forget what up front (I think 44 as well). He has and automatic and 3.73 gears and is running 35s with no problem at all, he said it doesn't struggle on or off road. What's the deal? Is the tranny different between '03 and '04?

Then he's too stupid to know what he's missing out on, plain and simple.

You're not going to have any "problems" with 3.73 gears, it's just going to be far from ideal with that gearing and 35s. Guarantee if this guy put the proper gears in he would be kicking himself for not doing it sooner.

So what you have here is simply a case of someone who merely doesn't know any better.

The 42RLE came in all 03-06 TJs with automatic transmissions.
 
My apologies as I know somewhere on here I asked this question on a thread but I can't find where it is, hence this thread.

2004 LJ automatic.
I have Dana 44s front and rear with 4.88 gears and I am running 33s x12.5 on 15" rims
I was told DON'T go to 35s unless I go to 5.38 gears because of the OD in this transmission and how it LOVES to stay in OD. I have experienced this even with the 33s where I will kick the OD off when getting on highway ramps or up long hills annoying but still only a first world problem.

I met a guy with a 2003 TJ who is running Dana 44 in the rear and I forget what up front (I think 44 as well). He has and automatic and 3.73 gears and is running 35s with no problem at all, he said it doesn't struggle on or off road. What's the deal? Is the tranny different between '03 and '04?
First I'll say I'm running stock 4.10 gears with a 5 speed and can't tell you if you need new gears.

We have a lot of really experienced jeepers who have a mind for perfection and their advice should be heard on this site. That said, compromises sometimes have to be made and that's your choice. There are likely lots of happy jeep owners running 4.88s and 35's who don't know the difference or couldn't afford a costly regear (also there's lots of folks with your transmission and 5.38s that are having vibration issues).

I say if you want bigger tires and your suspension / brakes / steering supports it, go for it and use the skinny peddle a little more. The jeep will still move down the road with 4.88s
 
First I'll say I'm running stock 4.10 gears with a 5 speed and can't tell you if you need new gears.

We have a lot of really experienced jeepers who have a mind for perfection and their advice should be heard on this site. That said, compromises sometimes have to be made and that's your choice. There are likely lots of happy jeep owners running 4.88s and 35's who don't know the difference or couldn't afford a costly regear (also there's lots of folks with your transmission and 5.38s that are having vibration issues).

I say if you want bigger tires and your suspension / brakes / steering supports it, go for it and use the skinny peddle a little more. The jeep will still move down the road with 4.88s

Can you explain the vibration issue you are referring to?
 
Can you explain the vibration issue you are referring to?
I can’t as I don’t have those gears. But I’d read around searching 42RLE 5.38 Vibration and a few threads should show up. Every jeep is different though so don’t want to scare you off since I don’t have the experience.
 
Can you explain the vibration issue you are referring to?

If you read the following thread and the threads linked within it you will learn more than you ever wanted to know about a harmonic/vibration that evidences in some but not all TJ's after regearing to very low axle ratios such as 5.38:1:

https://wranglertjforum.com/threads/install-report-yukon-ya-wu-08-manual-hub-conversion-kit-and-vanco-16”-big-brake-kit.18025/

These vibrations can be reduced and sometimes eliminated by careful adjustment of axle pinion angles, but not always. As you might surmise by the title of the thread I am suggesting that you review, this issue is resolved completely by converting to manual hubs.

If someone tells you that they have a TJ with 4.0 engine, 42RLE transmission, 33" or larger tires and are not getting any vibrations at all after regearing to 5.13 or lower (numerically greater) gears, be sure to ask whether or not they have manual hubs.

.
 
Last edited:
My apologies as I know somewhere on here I asked this question on a thread but I can't find where it is, hence this thread.

2004 LJ automatic.
I have Dana 44s front and rear with 4.88 gears and I am running 33s x12.5 on 15" rims
I was told DON'T go to 35s unless I go to 5.38 gears because of the OD in this transmission and how it LOVES to stay in OD. I have experienced this even with the 33s where I will kick the OD off when getting on highway ramps or up long hills annoying but still only a first world problem.

I met a guy with a 2003 TJ who is running Dana 44 in the rear and I forget what up front (I think 44 as well). He has and automatic and 3.73 gears and is running 35s with no problem at all, he said it doesn't struggle on or off road. What's the deal? Is the tranny different between '03 and '04?

What you don't know, you don't know. Hard to believe that people feel no difference when jumping up 6 tire sizes. Probably because 35's look rad and re-gearing is expensive.
 
  • Like
Reactions: StG58
I’m on 33’s with the 42rle trans. It’s on 3.73 and I definitely want a regear. It’s not too bad driving on level ground but I do feel I need more power on hills. The one thing that does save me is the o/d off switch on the dash when I start getting hilly. I’m saving up for the regear. I also am planning on doing selectable lockers so I unfortunately won’t have the money to do everything I want for a while because I’m looking at almost 5000 in parts.
 
If someone tells you that they have a TJ with 4.0 engine, 42RLE transmission, 33" or larger tires and are not getting any vibrations at all after regearing to 5.13 or lower (numerically greater) gears, be sure to ask whether or not they have manual hubs.

.

I would very likely not ask. The vibration issue while annoying enough to want to burn the rig down to ashes, is not as common as a very vocal minority makes it out to be. It is very much like the bad rap the 42RLE gets for being a crap trans and it really isn't. It is an okay trans.
 
I’m on 33’s with the 42rle trans. It’s on 3.73 and I definitely want a regear. It’s not too bad driving on level ground but I do feel I need more power on hills. The one thing that does save me is the o/d off switch on the dash when I start getting hilly. I’m saving up for the regear. I also am planning on doing selectable lockers so I unfortunately won’t have the money to do everything I want for a while because I’m looking at almost 5000 in parts.
You need to shop around a bit. A pair of selectable lockers with master install kits are roughly in the 2000 range, labor to toss them in shouldn't be more than 500 an end. Where are you getting 5 grand?
 
What you don't know, you don't know. Hard to believe that people feel no difference when jumping up 6 tire sizes. Probably because 35's look rad and re-gearing is expensive.
I've mentioned before that I quit participating in gearing discussions several places after being jumped on over and over by the idiots running 3.73's because they are "stronger" and they work just fine even in hilly country with 35's AND 37's. Then the shops that recommended that combo jumped in to help the damn dogpile.
 
I'm running 35's, 42RLE transmission, with a 42RLE transmission and I'm not getting any vibrations whatsoever.
So what, 16 forward gears now? I'm pretty sure an extra trans is more expensive than a hub conversion, and I suspect that you are deriving some benefit from running one?
 
You need to shop around a bit. A pair of selectable lockers with master install kits are roughly in the 2000 range, labor to toss them in shouldn't be more than 500 an end. Where are you getting 5 grand?
It’s a 30/35 Jeep. I’m looking at super builds so I’m adding in axle shafts. Throw in wheel bearings and ball joints. That’s what gets me to 5k. I can’t afford to brake down on the trail because my wife would probably never want to go wheeling ever again so I have to go over kill from the get go. That way I don’t get stuck doing what she wants to do on the weekends.
 
It’s a 30/35 Jeep. I’m looking at super builds so I’m adding in axle shafts. Throw in wheel bearings and ball joints. That’s what gets me to 5k. I can’t afford to brake down on the trail because my wife would probably never want to go wheeling ever again so I have to go over kill from the get go. That way I don’t get stuck doing what she wants to do on the weekends.

You don't need a Super 30 to go with the Super 35 and you don't need a selectable up front. The only one you are unable to stage out is the Super 35 as that all has to be done at once. The front can get geared and locked with a auto locker of some kind and then the shafts added later. That and a spare set of stock front shafts with a bit of knowledge and a few tools will probably last you a very long time on the trails until you can get some alloy versions in there.
 
  • Like
Reactions: JMT and BugoutJeep
ya saw some guy bust the ear off his front axle shaft 2 weeks ago on a jk and have to fix it on the trail. I know I can swap it out but all I can think about is how shot my nerves would be hearing about how she could have been at a winery or a bed and breakfast and now she has to sit on a rock and do nothing for 2 hours while complaining. That’s why I just would be better off doing a super 30.
 
  • Like
Reactions: AustinJeepTJ
ya saw some guy bust the ear off his front axle shaft 2 weeks ago on a jk and have to fix it on the trail. I know I can swap it out but all I can think about is how shot my nerves would be hearing about how she could have been at a winery or a bed and breakfast and now she has to sit on a rock and do nothing for 2 hours while complaining. That’s why I just would be better off doing a super 30.
Just get a pair of cromoly front shafts. Spend the super 30 money elsewhere.
 
  • Like
Reactions: JMT