I have a JK Sport with 3.21's and 33" Goodyear MT/R's with Kevlar. Not happy with the power that I lost, so, I got me some Yukon 4.88's, Zip Lockers for front & back, compressor, blah, blah, blah. My problem is this, I am concerned about fuel mileage with this set-up. I know I will have to go to 35" tires with 4.88's, and at least a 4" lift. What I need to know is this, does anybody have the same engine as I do and the same or other gear manufacturer, that can tell me what kind of fuel mileage you get on the highway? This is my DD, so I don't really wanna bust my pocket book on gas. Guys, I just need the 3.8 engines only plz. I know the 4.0's got better, the 2012's are better, I just need someone to tell me what I am in for so I can decide to just put 4.10's or 4'56's and stay with 33" tires and call it good. I studied the charts, and I know what kind of RPM I would turn with 4'88's. My question is fuel mileage. Can anyone give me some input? It would be highly appreciated! I would love to go 35's and 4.88's, just gotta watch the checkbook! Thanks!...

 

Can't help ya with the gearing info but 4" is A LOT of lift simply to fit 35's. 2.5" of lift would be a lot better for ya

 

My set up is in my signature. I get 13 city and 15 hwy

 

If the mpgs make a big difference, I would recommend stepping down to rubi take-offs and calling it a day.

It would take you at least 50,000 miles to break even on the cost of a regear.

 

I have a 2011 JKU auto Rubicon with 35x12.5 and the stock 4.10s and it is a dog I never get to use od. Any small grade and it starts hunting for gears. I got 13.5 mpg highway for a eight hundred mile trip. I am going to install 5.13s very soon. In town driving is around 11 mpg. I don't recommend 4.10 and 35 in tires with an auto.

 

I have a 2011 2 dr, 3.73's, auto, 18/59 springs, Rubi take offs. I get 16-17 in the city and 18-19 on the highway. I will be adding Teraflex Leveling Kit in the future. Plan on running 35's. Might trim the fenders.

 

4.10s; 4.88s; 5.13s once your at speed, the major cause of loss of fuel efficiency is aerodynamic drag. The second is rolling resistance of the tires. So no matter what gearing, less drag by less speed is key to increasing mpg. A car going 200 mph uses over half of its horsepower to overcome air resistance. Our Jeeps have aerodynamics of a car traveling with the belly towards the wind.

 

As usual, I forgot to mention I have a 6 speed manual. If I go with 4.10's, I will stay with 33" tires so I can use OD. If I want my Jeep to go with the monster look, I'll put 35's with the 4.88's. Would I be OK with a 2.5" lift? I would figure I would have tire rub on the fenders like I have now with 33" tires and no lift. This is a very hard decision to make and I only wanna make it once. Thanks for all the input guys. I wanna get this over with so I can start on other upgrades.

 

What are Rubi take-offs? Call me a dumbass, but I have no idea.....

 

07 auto 2 door with 4.10's and 35's. I'm runnin fierce attitudes and i get a constant 15-16 mpg highway and city. I'm in northeast Tennessee so it ain't flat, and sometimes you gotta bite the bullet and let off the skinny on grades and let em pass you instead of pulling 3.5 k rpm if you care about mpg's. Tire pressure, fluid maintenance and a tuner are pretty much the only way to improve it.