I just got installed a 3 1/2 left with 17" rims, 37 " mud tires and I also put in a drop in K&N air felter. Before the installments I was ave 18 miles a gallon, but now I am down to 14-15 miles a gallon. Is this a norm? Is there anything I can do to get better gas miles?

 

Sell it and buy a prius

 

or a Smart For 2

But seriously, what gears are you running?

if you went from stock to 37' you added HUNDREDS of pounds to your rig.... and made them harder to turn...

that and you are travelling farther on 37" than stock...remember the circumfrene is bigger and your Odometer goes by the revolutions of your Hubs, with stock tires factored in for distance....

 

Moved to the appropriate sub-forum. Welcome and I would start with regearing.

 

I'm running stock 4.10 gears with 37's and i get about the same milage. When pulling a steep grade or wheeling i get more like 9 mpg. 5.13 gears are going to be installed on mine soon though.

 

it is normal to drop on your mpg after instal of lift and big tires, especially 37's.
did u reprogram or "flash" the computer for bigger tires?
if u did not flash, then your shift points on the tranny will be afftected, so will your speedometer, and mileage. running 37's and auto tranny, it is recomended to regear to 5.13.

but regearing to 5.13 most likely will not increase your mpg but will fix other problems that u have with stock gears. in some instances you will get better mpg. i regeared from 4.10 to 5.13 and noticed no increase in mpg, but i got my power back, im not using overdrive like it use to on the interstate and many other advantages. besides the lift, regearing was best mod i did to my jeep. i had to wait 8 months after the lift to afford to regear, but i also added arb lockers at the same time to save on labor coast.

unfortunately, after u lift and throw on 37" shoes, there isnt much u can do to get the gas mileage back. seems to be people are running anywhere from 12mpg to 18mpg after lift and big tires.

u need to flash the computer and depending on what gears u have currently, its liveable untill u can save up for new gears. dont bother with the dealer for flash, as they cannot do it. people are always selling the programers used on here for cheap and even brand new is cheaper than what it used to be.

 

As stated above, there are a lot of things that make sense with your milage drop. Leave OD off, get some sort of programmer to get your speedo working correctly and correct your shift points. That in itself should have you see a somewhat improved mpg efficiency.

 

15 MPG with a lifted brick on 37 inch tires? Sounds good to me. I don't get 15 MPG with my Jeep and I still have the stock tires on it. I don't drive aggresivelly at all. I wonder why I only get 12 MPG or so when I hear all these people getting ( and complaining about ) getting 18 or so.

 

Yea thanks captjay I never flashed or regeared the jeep. Is regearing something easy to do?

 

i only get 14 all highway with 33s