Panhead5

Getting ready to go to BF Goodrich KO2's in 37 which actually measure approx. 35.5 on my 2014 JKUR auto. There's a chance at some point I may run 35's again maybe seasonally etc or if I get tired of the 37's . The question is which would be a better choice 4.56 or 4.88 ? Please don't suggest 5.13 not going to do it . It's a daily driver and I live at 750 above sea level and once or twice a year go out west at higher elevations to run the trails . Thoughts ???

urmyboyblue

My 14 is my daily (41k already!!!). I'm running 37" open country's which are 36.xx and I run 4.56 and it's heaven on and off road. Off road it just eases up things. On, I can still pass cars and get on from on ramps easily. Buddy 37 and 4.88 and his rpms at 70-75 close to 3k. I'm maybe around 2500-2700.

ZombJep

I am running 37" KO2s with 5.13 and wish I could get 5.38s but can't because I have a 30 up front.. Had the 5.13 with 35" KM2s and it was perfect. Of course it depends if you have an auto or stick. Mine is an auto. Still have a hard time pulling a small pop up trailer up hills. Just my opinion.

TN_Vol_Jeeper

Yeah. As a guy with 4.56 gears, and only 35's (with the 3.6), I'd tell you to go low 5's. Probably mid, if you're driving an Unlimited. My 2 door does pretty well, but I still have to kick it into 5th to accelerate up small hills on the highway. I wouldn't personally want to go above 4.56 just because I STAY on the highway in mine, so still averaging 19.2 mpg is nice.

PsychoCupcake

I'm with you. I think anyone suggesting 5.13 or 5.38 is nuts. And I mean no offense to anyone but your driveshaft isn't meant for those kinds of rpms at highway speeds. Especially for a tire that is measuring at 35.5".

So here is my take. Go with 4.88 in case you ever go with a different tire in a 37. My MTRs are about 36.5" and I'm running 4.88 in my 2012 auto. I think it's perfect. I know, other people will say their 5.13s or 5.38s are perfect. I'm also at sea level.

Just my two cents.

pbujku13

I have a 13 4door Sport . I just went to 4.56 in a D30 on my 315/70R17s (now seem to small/light for that gearing) from a 3.73, with a plan to replace the tires soon to KO2 37s. the KO2s run small; true 35" tires and 37Ko2s look very close in size next to each other... with a D30 I didn't want anything with smaller teeth - since you have a rubi D44 you can go higher I would suggest if you are already set on the tire and adamant you aren't getting a larger or heavier tire I think you should go 4.56 based on the RPMs and usage you mention..

larry0071

I run 4.88 with STT Pro 37" tires. At 65 MPH I'm at 2650 RPMs. I get around 14.5 MPG at 65 MPH, 65 is my highway cruise speed. I find the 4.88 gear to be about perfect unless your at 13,000' elevation, at that elevation I think any gear isn't enough!

shabbernigdo

2012 manual rubi. im going with 4.88 personally. i have 35's on heavy beadlocks with steel bumper front and rear so ive added a bit of weight and i would like 6th gear to feel good agian. 4.88 at 70mph is about 2800 rpm which is just at the tip of powerband. 3k isint even half of what the engine is capable of and it has no problem with it.

RedSyndrome

I have a 2013 Rubicon with 37's and 5.13s. I do a lot of crawling, but with the 4/1 transfer case, the 5.13's are a bit of overkill.
Also running down the highway at 70mph it tacs at about 2900.
If I had it to do over again I probably would go with the 4.88s, which btw brings the rpm back to stock.

I try to go on Jeeps runs 1-2 times a month, and 2-3 trips a year, so I am off-road a lot and enjoy the 5.13's.

If you stick with 35 inch tires and the stock 4.10 gears, you can enjoy yourself and save some money.

numbah1

Mine is a 2012 JKU on 37" Nitto Trail Grapplers. I'm running 4.88's and I love it. I'm able to chirp my tires and still manage to squeeze 18 mpg on hwy and 16 mpg (mixed). As for rpm's, I usually only drive @ 60-65 mph on the hwy with my revs around 2200-2500 rpm.

Off-road it just works wonders. If I could do it all over again I'd stick with the 4.88's until I get bigger axles and then swap 5.38's into them (for 40's).