Hello. I am new to this forum, but belong to a few others. Hope I won't get flamed to bad. I did try searching, but could not find the results I was hoping for.

So this being my first Jeep I have a question. I have a 2010 2 door Sport. I want to do the BB lift and 35's. My delima is the gearing from the factory. My window sticker says it has 3.21. I don't really want to go all the way to 4.10 because this is my daily driver and I want to maintain some respectable fuel economy. I dont do much off roading. Mud and sand mainly and never rock crawl. So my long winded question is what gearing would you recomend for 35's that will give me enough power, but still run 75 on the highway and get a decent MPG? Thanks in advance.

 

I spoke too soon. I just found a thread that shows the gearing chart for RPM/ tire size. It looks like 5.13 might be best bet?? Also wanted to mention that my Jeep is a standard.

 

I wouldn't run 5.13's personally if you aren't going to be rock climbing.

Try a superchips flashpaq.

I'm running 3.21's with 33's it was a little slow. I updated my tune with the flashpaq and it was way better than stock.

Personally I'd go that route for 300 or so dollars rather than 1000+ to re-gear at which time you'll most likely want the flashpaq anyway to change your axle ratio and tire size to correct your speedo.

So I'd start with that and see how you like it

 

Browse any of the hundreds of gearing threads and you'll find that the suggestions in the FAQ's are pretty universally accurate.

For 35's:
4.88's with a manual (some prefer 4.56 or 5.13)
5.13's with an auto (some prefer 4.88, or 5.38 for those that have rubicons)

With 3.21's, there is no chance of a flashpaq coming close to the performance gain of re-gearing. Will it help? Of course. But nowhere close to gears.

As you've already seen, that chart takes a lot of the 'opinion' out of the decision and puts it into perspective with numbers you can understand and feel...

 

Thanks for the quick suggestions. The more I read the more it is looking like 4.56 would give me the best mix of power and MPG. I live in flat Gulf Coast Tx and really only use the 4WD for some mud and sand getting to fishing holes...I do about 30 mile round trip at 70/75 MPH for work everyday. Am I making a sound desicion here?

 

i have 35's with 5:13. before the new tires and gearing (3.73 prior), i would be at about 2,000 rpm at 72 mph. now i'm at about 2,500 at 72 mph (actual speed, not what the speedometer says). when i maintain ~75 mph, i am around 16.5 mpg. i calculated it with my 2 last tanks of gas (70 mile highway commute, with pockets of traffic). before, i think i was around 20 mpg.

you may want to consider 4.88. this should get you (slightly) better mileage than the 5:13 and still give you some power to get your jeep moving. once you throw on the 35's, you have to accept that you will lower your mpg.

also, i would stay away from max traction tires if you are looking for better mileage. my car tends to roll to a stop much sooner with the mud terrains.

 

You are on the right track. The 4.88 coupled with the manual will give you the best performance. By installing 4.56s you will bias your choice slightly towards fuel economy, which you said you consider important.

 

That's exactly right. With the gear selection you're looking at you're going to be able put 50% more power to the ground, and with a Flashpaq you are going to be in the range of 10%. A Flashpaq can make up the difference between the next size up from 3.73s to 5.38s, but as soon as you need to move more than one increment of gears or upgrade from 3.21s nothing is going to take care of your needs like a steeper set of gears.