I think everyone knows that their mpg is going to drop but I think they are asking for any tips on getting better mpg. Don't see any harm in it.

 

You guys get horrible gas milage with 35"? I thought 14 MPG was good.

 

Try different gas stations. I honestly get better mpg at different places.

 

OK, heard that one before. I put $4k worth of fuel in my JK for 2011. I didn't buy it for fuel mileage. Should I just walk away from a prospective solution to provide better fuel mileage? A single mpg gain in efficiency puts a couple hundred bucks in my pocket, which for me is at least worthy of entertaining.

 

This helped me substantially!!

 

If you throw 35's on is your computer actually calculating it right? Will superchips fix this?

 

I am running 33's with a 2" lift and on the same trip up North three weeks ago I had cruise on at 70 and the jeep was constantly switching gears and on the slightest incline it was downshifting. I averaged 14.2mpg.

On the same trip home today I ran between 55-60(because of a snowstorm) and it seemed to keep the rpm's right around 1500 and my mpg jumped almost 4mpg on the highway.

For me when I use cruise it hammers the throttle to maintain the speed forcing the jeep to downshift much more.

 

All things being in line with tire size and gears, you will always see a fuel mileage drop off with extra velocity once you attain speeds over 50mph. Not that aero drag doesn't exist prior to these speeds, just that the exponential compounding really starts piling up.

At 55 or 60mph, you were making enough power to roll over the overpasses and the small hills we have here in the great lakes region. At 70mph, you're about 15% short of the power you need to roll over those grades without kicking down. Add in some crazy wind gusts generating from the lakes this time of year and you have a further need for power to combat head and crosswinds.

Re-gearing will give you better efficiency at these higher speeds. OD off is probably a little steep for 3.73s and 33s at 70mph, but worthy of an experiment to give you a window of where the appropriate gear set is. With appropriate gears you're going to reduce the frequency of downshifts while also keeping your vehicle from unlocking the converter and running in open loop when the throttle is depressed more than 75%.

 

Did you recalibrate your speedodmeter.I put the same tires on my '07,checked speedometer with a gps and found it to be off by 4 mph.This will effect the mpg reading.