Hey I have a 2012 auto 2dr with 35"s KM2, 2.5 lift and all the steel front/rear bumpers.

I get my gears redone in 2 weeks, I want 4.56 but the mechanic keeps says 4.88, and yes I seem the chart 1000 times. Most of my driving is highway during the week.

My question is anyone with 4.88 auto and a similar set up? What's the real world rpms at 60-65 mph?

Or should I stick to my guns with 4.56? Thanks

 

I've got 4.88 in my 2012 JKRU with 37" tires and it seems about right - about 3000 rpm at 70, but my mpg's really drop above 70. What gears do you have now? If you have 4.10's I would say save your money and don't re-gear since you are driving mostly highway miles. If you are running 3.21's or 3.73's, do you know anyone with 4.10's that would let you test drive it? I think the 4.88 will be too low for you with 35's.

 

I have 3.21 now. And unfortunately I'm the only one I know into jeeps around here. I figured 4.88 is to low , thanks !

 

I have a '12 4dr, 35"s, steel bumpers, 4" lift.
In addition, most of the offroading stuff is constantly on the Jeep.
It's a Rubi, so I have 4.1 gearing.
Before re-gearing, I decided to see how it does with the 4.1 . It goes nicely, good acceleration.
Maybe a bit lazy showing the 'ECO' on highways...

IF I ever re-gear, it'll be the recommended 4.56 .

Yours is a 2dr, so it's lighter and has a better power/weight ratio than my 4dr.
4.56 will, IMO, be perfect.
I really don't see how you'd benefit from 4.88 . Your engine will RPM higher for no reason.

 

Why regear? I've got a 2013 with 37's and 410's and it seems just fine. My Nitto 37's are certainly heavier than 35 KM2's. save your money and stick with what you've got. You just wouldn't see that much of a difference with 456's.

 

2008 JKU auto 35s and just got 4.88s couple months ago. At 65 on the freeway I'm just a touch above 2000rpm. Works fine for me.

 

He has 3.21's. how would he not see a difference going to 4.56 or 4.88

Yours is a bit different since its an 08. Op has a '12..4.56 will be good, but 4.88 will work and leave room for when he is ready for 37.... Lol a post above shows a '12 with 37's and 4.88 at 3000 rpm @ 70 mph seems a bit high. Maybe not a true 37

 

My '12 auto w/ 4.56 and 35" duratracs sit at ~2700 rpm @ 70mph, and its perfect. 4.88's may be too low for you, but like someone else mentioned, it may give you a bit more room to grow. Although 4.56's and 37s wouldn't be bad either.

 

I'm running your exact setup and I'm am going to 4.10s when I regear. I have 3.21s now and have seen a 2013 rubi auto with 4.10s and 35KM2 at 2500 at 70. That's right where I want to be.

 

Thanks for the replies, ill prob go with the 4.56 cause it's kind of hilly on the north shore here. But I'm glad to see I'm not crazy, I figured 4.88 was too low idk why he keeps pushing them lol