So, I am new to the forum .. I just recently purchased a used 2012 Jeep 4 Door JK .. Unfortunately, I was am stuck with the 3.21 gear ratio.. I am ultimately going to lift with 35s but because of cost, there is a good chance that I'll have to do this in stages..

If I go 4.56, am I going to be way over geared? Or should I go with 4.10 .. I've seen several opinions that the 4.10 are fine with 35s. Anyway, thought I ask for some opinions.

 

I have been going back and forth on this too and I think I am going 4.10 as I spend a fair amount of time at 75-80mph and am not a rock crawler. I think 4.10 will be a good choice for 33-34". Being I am not a rock crawler no reason to go bigger then 34's

 

I have a 12' with 3.21's also. Currently running 2.5" RK Stock mod lift with 35" General Grabbers and don't mind it at all. The Grabbers are some of the heavier tires and in the winter I've been getting 16MPG's and expect a little more in the summer. I'd say try out the 3.21's before you upgrade if you are not a heavier wheeler. I do some mild wheeling on about once a month and don't mind my setup at all.

 

Maybe this can help

 

Both ratios are good, it depends on your use.
Much offroading?
What type of offroading?
Much highway speeds?

I have a '12 4-dr and 35"s, the gearing is 4.1.
There's no lack of power. The 'ECO', however, rarely lights up.
With 4.56, the r.p.m. would of course be higher, but the engine will "see" less load.
I prefer the 4.1 .
The difference between the two is about 10%, which isn't much, and you'll be OK with either, as you can see in the table.

However, if you think you may want 37"s in the future, the 4.56 will be waiting for them.

Tire sizes are, BTW, nominal. The true size is typically about 1" less, so most 35"s are actually ~34".
The table is for nominal tire sizes.

 

Hey guys .. sorry for the delay .. Was out camping for the weekend.

Thanks for all of the input.. I am not sure I'm much closer to a decision but it does sound like 4.10 might be a viable option if I have to do things in stages.. I'm a bit worried about being over-geared with the 4.56 on 32.5" tires..

 

i'd say 4.56... I hear 4.10's for a JK dana 30 are pretty expensive (unless you can find some used taken off a 2007 sport/saraha)

 

Definitely get the tires first. Drive it and see what you think. 35's here 3.21's and 60
Miles of driving a day

 

I got a 12 JKu I put 456s in with 35s bfg km2s they run on the small side 33.5 on the jeep. I like the set up would be better if I had a true 35" but run about 2500 @ 65 a little over geared but I pull a pop up camper when we out for weekend trips.

 

35's with the stock 4:10. I'm pleased all the way around. Off road, crawling, hills. Highway and back road running as well in the mountains. No complaints. I don't tow on a regular basis.