Hello all, I have an '11 two door sport, six speed jk and just recently put 33 inch Mtrs on it. I used to have rubi take offs which were bearable with the 3.21s but not the 33s. Im about to pull the trigger on some 4.88s with a new front carrier, I do plan on 35s in the future but not anytime soon. I know theres a search button and that it might be running a little high on the highways but I just want some input from real experience with guys running 4.88s and 33's on a 6 speed. If anyone has rpm #s at highway speeds and mpgs that would be appreciated. Also any input on your gear and carrier selection would be nice as well. Thanks!

 

I'm in the same boat. Be interested to hear what everyone has to say.

 

Im not running 33's but Im running 35's with 4.56 and at 75mph my rpm's sit at about 2800-2900 at 80mph I just barley over 300rpm and at 85mph Im about 3150rpm. I have an 2007 jku 6spd.

 

Here's your answer:

https://www.jk-forum.com/forums/modi...-205615/page2/ post 20

(It says 2012, but on post 20 it's the table for 2011)

 

Yellow is acceptable, Green is best of all worlds for a daily driver and blue is best off road/crawl performance and a fair daily driver.

So your ratio depends on how you use your Jeep, the chart gives you the math behind it the gears...

Bump for wisdom from the real world

 

I drove around on my stock 31" SRA tires after re-gearing to 4.56 for about a month. Basically 1st gear was completely useless on the street (it would get you up to about 5 MPH), and at 60 MPH the engine would spin at 2600 RPM in 6th gear. I'm certain your RPM range would be fairly much the same with 33" tires and 4.88 gearing.

BTW, that graph above is for a 3.6L engine.

 

Oops my bad here's the one for 3.8:

 

Stupid phone...

 

I have 4.88 and 33s on my 2009 Unlimited with six speed. I geared to 4.88 to prep for 35s which will happen soon. At 75 mph the engine is turning around 3300 in sixth gear. I average 16mpg around town. Might be better but I don't drive like a gramps. Not sure about highway mpg because I'm never on the highway for more than a couple miles.

 

You must like to really gun it off the line lol We've got a 2010 JK 6spd/3.21 gears and 35s and it's deff enough to move the Jeep. The Jeeps kinda gutless anyways though. It came with Rubi rims/tires from the factory though and it was fine, never felt like it needed more power.

4.88s are great with 35s, but anything less and your RPMs will be high on the highway and your MPG will decrease of course, but not by a huge amount. It may go down around town also as you'll probably change your driving habit to use the skinny pedal even more lol