JPop

Mileage is going to greatly depend on the roads you are traveling. For many, 4.88s would see them dropping out of OD a fair amount at highway cruise speeds. 5.13s would drop out somewhat less. Were only speaking about a 5% difference, and there certainly won't be a 5% difference in fuel mileage one way or the other.

The key is really preventing downshifts for the typical grades you may encounter. Unlocking the converter and downshifting is what robs fuel mileage and staying in the sweet spot of the power band (23-2700 rpm) will provide the best drivability. Then there isn't much question as to what will do better off road where no one will complain about having a too steep gear set.

So look at the chart and measure your actual tire diameter. That will put you where you want to be and be leery of anyone that doesn't drive a JK making suggestions.

storch

Good info thanks.
if there is no head wind or uphill and my tires are aired up to over 35lbs I can pull OD with the 3:73 stock gears 70mph = about 1800rpm and jumps up to 2800 in 3rd, I takes very little to cause downshift, I do have a Hypertech / K&N and aftermarket Exhaust may help a little.

there seems to be nearly a 1000 rpm differance between OD and 3rd looking at the charts is it correct that I would pickup 500 rpm at 65 with 4:88 and 700 rpm with 5:13.
currently running in 3rd is more RPM than needed unless towing a small trailer.

Sounds like it will be 4:88 or 5:13 for sure.

Good prices on G2 gears and rebuild anyone have experiance with that brand?

hdrider

I was asking the same question some time back. I ended up going with 5:13's and am happy

Ryanc

Ive got a 6 speed, 35s, and 513s, freaking amazing. One thing to note, the difference in rpms between 4.88 and 513 is minimal. Dont fear the gear. If I had an auto, id go 538.

oeser

I have an auto with 35's and 5.13s are the only thing you should consider. Mine is a DD and I drive on the freeway every day. I think I could have gone to 5.38s and been fine too. Very glad I didn't go with 4.88s. Good luck.

storch

I think i will go 5:13 since i will be towing a small boat and Dirt bike trailer next summer.
anyone use the G2 gears

Dronac

What would be good for 33s/auto trans that does alot of highway driving to maximize mpg? 4.88 or 5.13?

Unrelated, but I did some tests with engine load readings with my flashpaq. With 33s and an auto, at 75mph I was running near 100% load on flat roads! With OD off, the engine load went down to 40% with a max of 75%ish load.

jeepmedic

My JK gets plenty of use offroad, but its my DD as well. 5.13s are the only way to roll IMO. My mpgs went up from 12 to 16, and the acceleration is better, and no more down shifts on the interstate / hills.

I love it !!

RevyJKU08

With 33's and an Auto...look at the 4:88's but if you are even considering 35's in the future go with the 5:13's!

JeepersKreepers

Automatic...GET 5.13!!! I just got them put on today... couldnt be happier!!! in city driving is much improved! havent had a chance to test high way too much yet... Definately worth the price! Get them with Dave at Northridge!!