Dude, I'm just as up in the air as you right now haha. I was kinda waiting to see how you liked your 4.88s to be my deciding factor. I've heard people say that they went 4.88s and kinda wanted to go to 5.13s afterward, but I've also heard that people that go to 5.13s hate the highway mileage...... damn.

 

Around 16.... it did even better on a 7 Hr trip to Pittsburgh

 

To planman: I totally get what you are saying. I actually do have the lightest bumper combination I could find, the lightest tires, and no exterior add-ons that would hurt aerodynamics. Also, I do live in SoCal, but I was just giving Tahoe as a reference of a long drive. Ultimately, I have a feeling that I will end up with 5.13s because everyone is pushing me that way. I guess I would just like more info from people who have 4.88s, but they seem to be few and far.

To Robsjeep: That is better than what I get now actually.

 

Lol you must drive it harder then me..... I know my superchip helped too.... Do what's best for you and your type of driving..... Good luck.
Rob

 

So you lifted your jeep, added 35" tires and 5.13 gears and still get the same MPG you got when you were stock? Are you on crack or do you live somewhere that the laws of physics do not exist?

 

For your information sh*t head ..... I never said I got the same mpg as STOCK!!!!!

Can you see that anywhere in my posts???? I said before and after my gear change I never lost any mpg..... I was using a superchip before and after..... I was talking/comparing mpg before and after the gear change..... NOT stock vs all my mods.

I lost a bunch with tires, lift etc BUT gained some of it back with the superchip and when it was regeared..... And driving habits affect the mpg greatly...., I don't drive it like a sports car.... It's a jeep.
Stock I was getting over 16mpg easily.

 

I've got a rediculous amount of heavy mods on my '08 JKUR, 4" of lift, 35" tires on steel wheels.

5.13s + Superchip (87 Oct Tune) = 15mpg city, 16.4hwy (at 70mph). Last trip to FL, I got 17.6mpg highway.

I've driven over 20Kmi on this setup in the last 8mths, if you go with 4.88 you will be wasting your money with an auto tranny. As has been said, you have any slight wind/grade/hill, your OD will constantly fight itself ultimately killing your MPG. I can maintain speed (@70) at ~2300rpm and still use my OD on the highway.

 

Gears are my next mod. I have 34+ diameter tires on now with 4.10s. I am surprised at how good she is still accelerating in the city. I think the fact i have the Ripp headers and tuned with the Diablo is helping. I had planning on going with 4.88s but after reading all of this i may have to go with 5.13s. I don't imagine it would be a big difference going from 4.10 to 4.88 anyway?

 

put new yukon 5.13's in my jk 3 weeks ago. fuckin awesome is all i have to say. should have done it as soon as i got it off the lot. i'm turning 26k at 75 mph. cruise control works like a charm, and i'm getting upwards of 16mph. go with the 5.13's. you won't be sorry.

 

I think it has a lot to do with elevation above sea level. I live at sea level and this is about the mileage I get with a stock 2dr auto on stock 255's tires, and I drive it slow & easy.