Wgrin

First let me say that I have an 11 JK 6 speed manual. I have 315/70R17 tires which equal out to 34.5".
I had 3.21 gears and once I put on larger tires it was about impossible to reach 70. I had 4.88 gears installed against my first instincts.
I wanted to get 4.56 gears but was talked out of it by two different companies.
I ran an 80 mile run today to test the gears and this is my opinion. Anyone may chime in and I'd like to here from anyone in a similar setup to mine with the 4.56 gears too.
First have you ever ridden an 18 speed bicycle and been in 1st gear going down a hill? Know how you pedal and it doesn't feel like you are doing anything? That's kind of how I would describe my gears now. I am already in 3rd gear by the time I'm at 20 mph. My gas on the interstate only is at around 13.5 before I was around 17. Now with the 3.21 it was hardly ever in 6th gear and now I can drive up some decent hills (Ft Worth size) and not have to downshift. If you are not going to do much off-roading than I strongly recommend 4.56 no matter what the shop says you know if you off-road. I think maybe nice for 35-37 tires but 34.5 just has the engine at a higher RPM than necessary. There is no need to even use 1st gear from a red light because you'll shift at like 5 mph.
I was talked out of 4.56 and I should have stuck to my guns, they even tried to get me to get 5.13 which would have been silly. I haven't go off road with it yet and I dont do that much anyway so it may be good there.
Any questions just ask

plac

good info. the majority overgear "just to be sure". the problem with 4.56's is they are a bit harder to find than the 4.88's everyone uses.

brutalvette

Thanks for the input. When I regear I will put 4.88 in my '10 jku auto. After looking at the charts and considering the driving I do I think it is best for me.

keithsfd7

I agree totally, I have an 07 JKU with the same setup but they didn't have the 4:56s when I regeared. Maybe it will be better if and when I decide to upgrade to 37's.

frick316

I have an 08 jku. With auto in it running 3:73 gears with 33x12.50 BFG mt. And it is constantly searching for what gear to be In on interstate and highway. If I can't fix this with my vivid tuning the trans I'm going to gears next

XBlacky08X

I plan on regearing in the future and the shop I go to keeps insisting I get at least 4.88's. They are also trying to push me to get 5.13's as well! I have a 6spd and 315 Duratracs which measure about 34", so I am very indecisive in terms of what gears to run! I want good daily drivability and gas mileage, but also have and for 37's in the future. I just don't know.. Good input though!

CJ7nvrstk

I have been suggesting for quite some time that people are over gearing and am constantly being told by the "experts" that I don't know what I'm talking about. I wonder if they will show up on this thread to tell you the same thing.

plac

they always show up. my favorite gears are 3.21's.. i've had all 3 JK sizes.

jaybrown

Go 4.56 I have 4.88s. I wish I got 4.56. That was the plan until I heard that 4.88 gives you great performance. This is true but only in 4wd on the hwy and around town it sucks 4.56 will give you plenty of power if not more around town and on the hwy. I can pass in 6th gear on the hwy but It revs a bit high Even 4.10 is good and easy to find used. If you drive around town a lot it's better.

hammerhead

I have to disagree. 4.88 with a manual are perfect.