CJ7nvrstk

I know I will get flamed for this but I think this is an excellent choice.

For the cost, 3.73 to 4.10 isn't worth it and you likely would want lower.

On my 08 with an auto running 37s, I listened to the self proclaimed web wheeling experts and went with 5.13s with my 37s. I should have gone with 4.88s. So that's what I did with my 2011, 4.88s and 37s.

4.56s should be just right for 35s.

MarwanJeeper

higher is better for ur engine 3.8L
4.88 and 5.13 is better option

4.56 for new engine3.6L

Wandell

Have you experimented with just driving with the overdrive off? That will give you an idea of the rpms you would be turning.
Out of curiousity, how many of you just turn the OD off vs. regearing? I know it doesn't give you any effect in acceleration, but mine drives much better without the transmission constantly shifting in and out of OD.

resharp001

It seems that you can hobble by doing that when you're off by one bump in gearing and it just makes more sense as the money spent wouldn't be worthwhile, but once you require jumping at least 2 gear sets....there's no replacing a regear.

Wandell

One more monkey wrench in my plans to regear down to 5.13's. When we bought the JKU, my wife wanted to purchase a life time warranty that the dealer was pushing at the time. I agreed since we tend to keep our vehicles a long, long time. So, now afraid of warranty issues if I regear my axles. Obviously the ring and pinions would be covered by the gear manufacturer. But what else could go wrong that the dealer could blame on my changing ring and pinion gears?

resharp001

I have a coworker here with an '11 in the same situation.....and it's held him back from regearing for several years now. At some point though, you just have to throw caution to the wind and not worry about the warranty aspect. I'd much rather enjoy the jeep and have it drive properly.

Trail Jeeps

A lot of the typical rules about RPMs and fuel economy don't tend to apply to a 3.8 Jeep. You can step up the gearing 1 to two ratios over the conventional thinking with a JK 3.8 without many repercussions. The thing gets pretty much the same fuel economy no matter how much it is wound up on the freeway. It is more sensitive to hard work, i.e. taller gears.

I would recommend a 4.88 gear for a 3.8 JK with a 35" tire.

nthinuf

You recommended two different gear ratios for the same engine/trans combo within just a few minutes of each other...

I understand your meaning, though. Getting past the numbers, there is a bunch of personal opinion involved in the decision, and there really isn't a single choice that will work for everyone in every situation. There is a ton of information out there, it's all about each person doing their research and figuring out what is right for them. And as I mentioned above, not making a snap decision based on a few replies.

Rednroll

I noticed that also, but figured he didn't realize the OP was dealing with a DANA 30 and maybe assumed a DANA 44 on his 1st recommendation.

I'm still stuck between 4.56 and 4.88. I need to borrow someone's 3.8L auto with each and decide for myself unless someone can make a convincing argument one way or the other. I think it's kind of like splitting hairs and personal preference at that choice though. I'm currently leaning towards 4.88.

Trail Jeeps

A 4.88 is generally my recommendation for a daily driver on 35s, it's the right compromise between performance and strength for all. I was saying that a 5.13 is nothing to be afraid of as far as engine performance and fuel economy, but it comes with caveats that 4.88s don't. I guess I should have clarified.

There are TONS of opinions out there, but I will say that this advice is more than just our opinion. I'm not saying that I'm preaching the gospel, but we do have personal experience from dealing almost exclusively with these Jeeps for nearly a decade that leads us to our theory on how to match up tire size with gears. I'm also not saying other ways of doing it don't work, but we have definitely noticed consistent outcomes that hold true pretty much every time.

Whatever you do, a regear is ALWAYS a good idea and will yield noticeable positive results, and that is guaranteed!