kgw350

Im running 37s on a 2013 auto with 3:21s. Im in no rush to regear ordered a locker for the rear. I have my previous 2012 rubi with 5:13s to compare and the 3:21s are not that bad with the auto and new motor.

jarad

I believe you a refering to a Sprint Booster, and as i understand it, it is an amplifier for the drive by wire gas peadal. It just makes the throttle open faster.

Im running 275-65-20 load range E Goodyear AT/S. They are 34" tires. Very heavy though. And with the 20" wheels i think they weigh about 95lbs. I think my stock tire/wheel was 65lbs.
My 2008 JKU has the 6 speed manual and 3.23 gears (still).
The only performance mods i have are a k&n air filter and Superchips Traildash (that i installed last week).
I find it very tolerable to drive so far, and i live on "Mountain Rd"! I shelled out some cash for a good ebay deal on the Traildash mostly to correct my speedo/odo/average MPG/ (and traction control?).
I am hoping to also see some increased MPGs from the performance tuning, but it is too soon to tell. I do like it so far. (Feel like you dont get as much for your $ if you dont have a auto tranny, or rubi for that mater. But i am glad to get back the proprer info from my guages.)

If i could find the right deal i would love to replace my axle assemblies with some lower geared ones (4.56 to 5.13), but i can live with it for now.
I pulled a second gear start the other day! But not alot of creepin and crawling in 4lo.

FlameRedJK

Ya know, I honestly couldn't tell ya. I don't even know anyone that runs a manual lol.

E-Man

I'm running a 2012 JKUR auto with 35" KM2s. I had 4.10s in it stock, but re-geared last month to 4.88s.

Man, you guys have NO idea how much usable power you're loosing by not re-gearing. Power and accelleration wise, I feel like I'm driving a stock Rubi again. Highly recommended modification.

Pregnant_Monk

I think we all understand the power loss over stock considering a lot of us drove it stock for a while but is it worth the money vs other mods. I would say no IMO.

big dr

let me offer the other side. IMHO 3.21 gears are no where near the right gear for 35's. I fully understand the new engine has more power and torque; however, that doesn't mean you aren't stressing the entire driveline! I disagree that bumpers and sliders are more important, because you should not be doing that heavy of wheeling when you are that far out of gear. you will shorten the life of your engine, tranny, clutch or torque converter, and drive shaft joints. The mechanics of these vehicles is important to keep within tolerance. ( AS IF WE DONT MESS WITH THEM ENOUGH,,,, WE SHOULD AT LEAST STRIVE TO DO IT RIGHT)...... Does anyone agree with me?

flotto

I agree that regearing is ideal. I would like to after I get 35s it'll just take a while to budget it down the road.

Matthewd5

I recently upgraded my 2012 sport S's tires from stock 255/75/17 to 285/70/17 with a six speed and 3.21's and have hardly noticed a difference both on and road

If I go bigger i might goto 4.10's

Matthew

Terry Hesticles

What kind of mileage are you guys getting with these setups?

I'm looking at ordering some 35" KM2s this weekend for my JKU 6-speed manual, but am worried about the mileage dip as well as the added stress on my clutch and axles. I'll regear, but I don't know when. The only thing making me feel better about this over going with 33s is the fact that KM2s run small, with real world estimates at 33.x" at 30 PSI on mounted 35" KM2s.

Maniacal

I have 35" nitto trail grapplers 4" lift and 3.21 gears. I get 13.5-14.5 mpg with the 3.6 auto. I am upgrading to 4.56 gears this month. The 3.21 will hardly go into overdrive and has shitty power. I chose the 4.56 because I run a lot of interstate @ 70mph.