I have a 2009 JKU x and im planning on getting 35s but do i need to regear im running stock gear s with 3.8 motor

 

Drive it with 35's and then decide. Some are ok with stock gearing, some aren't.

There are some charts in the modified faq's. Use measured tire heights, not mfg spec height. For auto's, divide OD On rpm by .69 to get OD Off.

 

I would but i would really like to know because im 16 i mean like im still driving to school everyday i want 35 for good offroad use but i need good mpg too

 

No one can tell you whether 'you' will want to re-gear. It depends on which model JK, which transmission, which gears you currently have, where you live, where and how you drive, what 'your' personal preferences are, etc, etc.

Start filling in some information and we might point you in the right direction. Just remember that no one here is you.

For me, I thought my 4dr auto was undergeared/underpowered straight from the factory. With 35's, I had 5.13's, and swapped up to 5.38's when I replaced the front 30 with a 44. 5.38 was the right choice for me. Is it right for you?

 

I run a 3.8 with 4.5 inch AEV lift and 35s...what gears r u running and where do u live?

I have 3.73 and live in central Texas where it is flat so I am fine with stock gears.

I was also in the New Mexico red river area which is mountains. If I lived in that area I would regear.

 

He just told you how you would know.

Stock tires are good off road. Stock Rubi tires are even better. 35's can be much better, but it depends on which tire you get. Also, going to 35's will almost eliminate whatever "good" gas mileage you think you get now.

Are you worried about the cost of gas? If so, you're off to a bad start as you contemplate $1500+ for tires and $1000+ for a regear

 

I will agree, you can kiss any "Good" gas milage goodbye once you put on 35's. I used to have a 2010 2 door on 35's with 373 gears and a manuel trannny, it was fine and had enough power for me to get around and do some off roading. If you want to keep any gas milage I would suggest maybe a set of stock rubi tires or not to much bigger or more aggressive then them.

 

I have a 2 door 2009 x on 35s went from 321s to 488s I get 17mpg

Sent from my NSA listening device

 

3.8 auto 4.88s 34s here- wonderful.

 

2400 rpm at 70 mph, and 18mpg city.