New guy with questions

[TheNewWampsCat]

I’m planning on a Rubicon in the near future. ... so first question is I like the looks of 35s and am seeing you don’t really need a lift to run them but I’ll probably do a 2” anyway. I had been waiting for the diesel but have about talked myself out of it. Now here’s the question. My original plan was to regear to 4:88 so if in the future I decided I wanted to run 37s I could. Talked to my dealer about it and they’ll do it and I keep the warranty. I don’t really think that deep of gear is needed for 35s but why not? So my question is any real reasons to not go that deep? I’ve gone over in my head and don’t think it’s going to hurt anything except the wallet. What say you?

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[OL1970]

First off...do it, you’ll love the truck. Secondly I just went with 37’s and lift from the get go, not planning on re-gearing because i haven’t heard a whole lot of people thinking it’s absolutely necessary. Would be great for people to chime in if there is doom and gloom in my future by choosing not to go through a bunch of other upgrades.

 

[smlobx]

There is a chart on here floating around that shows the 4:10 gears and 35’s are a perfect match...
If you are considering going larger than a re-gearing may be needed..

 

[TheNewWampsCat]

Actually from what I’m reading 35s should go a little deeper but probably isn’t necessarily needed. But with going to 37s 4.88 is probably a little deeper than needed. Now I like the idea of the 37s but my older back doesn’t like the idea of changing those bad boys out. Hell the 33s are a pia now. Just what I need more to think about before buying this.

 

[RSK]

I plan to go to 35’s on my rubicon (4:10) when these 33 Falken M/T wear out. Pretty sure I’ll need a Tazer mini or Flashcal to update/flash the automatic shifts at that point. I’ll consider the lift if the 35’s don’t look right, but from what I’ve seen a lift might not be necessary with 35’s. If I like it with only the new tires, will be just over a $ grand for all.

With 37’s, a lift, re-gearing and flash might be needed, which gets pretty expensive.

 

[Renegade]

Regearing is mostly unnecessary with 37s, 4.10 gears, and the 8-speed automatic transmission. First gear is very low, allowing sufficient acceleration. 8th gear does become obsolete, but who really cares? 7th gear is also an overdrive gear, which is still 2 gears more than a JK. Everyone saying that you need to regear with 37s should drive one before making this recommendation. For reference, my prior JK had 4.88 gears and 37s. The JT kicks it’s ass!

 

[TheSolarWizard]

I’m planning on a Rubicon in the near future. ... so first question is I like the looks of 35s and am seeing you don’t really need a lift to run them but I’ll probably do a 2” anyway. I had been waiting for the diesel but have about talked myself out of it. Now here’s the question. My original plan was to regear to 4:88 so if in the future I decided I wanted to run 37s I could. Talked to my dealer about it and they’ll do it and I keep the warranty. I don’t really think that deep of gear is needed for 35s but why not? So my question is any real reasons to not go that deep? I’ve gone over in my head and don’t think it’s going to hurt anything except the wallet. What say you?

4.88 is too low for 37s and 35s fit s rubicon without any rubbing whatsoever. They look silly with a 2” lift.

 

[TheNewWampsCat]

4.88 is too low for 37s and 35s fit s rubicon without any rubbing whatsoever. They look silly with a 2” lift.

The 4.88s are probably to low.... after looking around and reading the 4.56 might be a better choice. In the past I dealt with putting 35s on with 4.10 and a 4.0 and lost gears. So the new one will have lower gears to start with. And if I ever decide to go to 37s it’ll be fine. Also the reason to lift it 2”.

 

[Renegade]

The 4.88s are probably to low.... after looking around and reading the 4.56 might be a better choice. In the past I dealt with putting 35s on with 4.10 and a 4.0 and lost gears. So the new one will have lower gears to start with. And if I ever decide to go to 37s it’ll be fine. Also the reason to lift it 2”.

I’m coming to realize that more lift may be desirable with the JT to reduce dragging over obstacles, even if a larger tire isn’t desired.

 

[Sgt Beavis]

4.10 is fine for 35s. Watch this if you're considering 37s.

 

[OL1970]

Wow thanks for posting that video, might be the single most informative best explanation have ever heard on the subject. Hard to argue with math!

So 37’s on a Rubicon should be running 4.56 according to this guys formula. I wonder how many have already done this with great results?

 

[Sgt Beavis]

Wow thanks for posting that video, might be the single most informative best explanation have ever heard on the subject. Hard to argue with math!

So 37’s on a Rubicon should be running 4.56 according to this guys formula. I wonder how many have already done this with great results?

Lot's of folks use that method. We've had ad nauseam level discussions about gearing on the JL forums.

Anyways, Based on the experience of others, I'm running 35s on my JLU Sport with 3.45s and I don't have problems driving up mountains. I think you're fine with 35s at the current gearing. But follow that method if you go larger.

 

[Shathawk]

I have an LE with stock gearing and 315/70R17 KO2's and the gearing feels proper. I am getting 20.6 mpg during highway driving at approx. 65mph.

 

[OL1970]

I'll report back with what I end up doing and how it drives/handles. I would say less than 5% of my driving will be above 50mph, and we never take long road trips (wife's benefits let us fly for free : ) If the Gladiator needs re-geared no worries, its good to have a resource like this forum to come back to for help. We are keeping the JLUR stock, maybe someday going up to 35's no lift.

 

[Renegade]

Wow thanks for posting that video, might be the single most informative best explanation have ever heard on the subject. Hard to argue with math!

So 37’s on a Rubicon should be running 4.56 according to this guys formula. I wonder how many have already done this with great results?

Math doesn’t lie, but you also have to weigh the cost vs. benefit. The lower and broader gearing of the new 8-speed transmission changes things vs. older Jeeps too. If performance remains acceptable, the cost to regear needs to be recovered in fuel mileage to be worth it in my opinion.

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