Well from recent experience...I have a 2012 - 4 door - automatic...35" tires...added bumper weight...stock was 3.21 gears...Installed 4.88...
HUGE difference in city and highway...I will admit revs a little high on highway 70 MPH 3000-3100 RPM...
No problem passing or keeping up...Otherwise would not change anything...Mileage about the same that i see...
With other gears transmission was always down shifting - these gears stays consistent...This is just my experience with gears...
Installed Yukon - professionnaly installed no problems at all...

 

I went with a Rubicon knowing I'd use it off road. and with bigger tires.

the factory 4.10s on my 2012 auto work just fine with 35s

this thing is wicked quick. Sure it could be quicker, but I'm very happy w/it.

 

....4.56s....

 

Did you reprogram for the bigger tires? If not, some of the perceived loss in mpg will recover with the reprogramming of the tire size.

 

The chart is not accurate for RPMs. It's off by 250-300 RPMs on many gear ratios.

That can be a huge difference for people who commute daily at hwy speeds for both MPG and life of their power train.

 

Well we went with the 4.88's, G2. Along with the Hyoertech Interceptor. Extreme improvement! Both in performance and in gas mileage.

 

Im thinking of going from 3.21 to 4.56 for my 13 auto. The installer uses g2 gears and swears they are fine. How come I see alot of negativity toward g2 gears?

 

We went with them because of cost, but several in our Jeep club used them as well. No one has had any issues. Not sure why they've gotten a negative rep.

 

The installer im using is very credible and runs g2 gears in his own personal rig with no problems. I talked with him about it and going to give it a go.

 

We're quite happy with them. Next will be the pumpkins.