I was going back and forth reading everything I could trying to decide on 4.10 or 4.56 for my '12 with 35's. I do a lot of highway driving and didn't want to rev too high. I went with 4.56 and think its perfect. The shop agreed that the cost to go to 4.10 wasn't worth it. I think you'd be very happy with 4.56 around town and on the highway.

Am in the same boat, but it costs around $800 in labor and oil to do the job, while there's a shop near Montreal that will do 4.56 for around a Grand out the door. And they specialize in Jeeps.

I have a '12 JKU Sport/auto and went from 3.21 gears to 4.56 gears with 35s. I live in the mountains and wheel it pretty often. Its fun to drive around town again and it spins right at 3000RPMs on the highway at 80mph. It doesnt hunt for gears anymore on the highway and its much more pleasant to drive. The rigs can handle the RPMs so just go for it. Hell, the rubicons come stock with 32s and 4.10s.

Just went from 4.10s to 4.88s in my '12, night and day difference! I'm running 35s and with the possibility of 37s for the next set of meats so 4.56s didn't make sense. I have a 6m and it turns just under 3k at 80 on the highway, or anywhere else you want to do 80 lol. I have never seen better than 16.5 on the vic and that was all highway driving, usually 14.5 around town. I saw 17.5 running around town and it did go slightly down once I hit the highway and rand about a 100 mile stretch, 16.9. I am still breaking them in, its not a daily driver but would not have geared it differently, 4.56s, if it was. Its so nice to hit an uphill stretch on the highway and not end up in 4th gear in the slow lane anymore!! Speedo has always been calibrated with the Procal.

Well i just went to 37s and im running stock 4.10 rubi gears and its fine. Plus bigger the gear smaller the pinion which means easier to break

Been driving on the 4:56's now for a few days. With 35's and 6spd man, it's perfect for a double duty jeep. Makes a good DD except the shift from 1-2nd comes pretty quick.
I'm getting about the same mpg as my 3:73 and 32's. Shift into 6th at about 60 mph.
Happy Happy Happy!

Thought I would follow up with thread. I did the gear swap on my 2013 JKU. I went from 3.73 to 4.56. I have the automatic transmission. I have Kelly TSR 315/70r17 tires. I corrected the ECM with Flashcal. The speedometer was correct before the gear swap, been verified against my GPS and a radar. I just finished the other day. My initial impression is great around town, but a bit over geared for the highway. My RPMs; prior about 2200; currently 2750; all at 70 mph. Picked up some MPG around town but lost some on the highway. My JK is first and foremost a daily driver. Just being honest with myself about its use.

I am going to drive it a bit more, and see how I feel about it and look at the MPG numbers some more. I kind of feel at this point, wishing I had just gone 4.10, like some of the effective gear ratio calculator had suggested.

I'm on my phone not sure where your located but if you don't like the 4:56, I would be willing to trade my 4:10's. Just swap both axles and be done.

Haha... Was thinking the same thing 😁


Sent while my wife wasn't looking...

Yeah. The Auto is a different animal. With 6 spd and 315 Duratracs (33.75"), I'm turning 2500 at 70.