So when I first had my 07 Jk with some Dunlop 32s I was getting around 16 mpg. No other mods were in place at the time. I did a 2.5" BB lift and put on the 33" (295) Nitto Trail Grapplers and now I'm at 12mpg. I'm wanting to go 35s but terrified of what MPGs I'll be at then. Regearing wont be happening until next year. Just seems that I had bad MPGs from the beginning and didnt expect to be where I am now. If there is a connection I have 3.21 gears

 

What a difference. You and I are running about the same equipment. I have an 08 manual with 17" 32's. I'm getting about 16.5 per gallon. 2 things:

1. Make sure you have plenty of air the the tires, and
2. Are you taking into account your speedometer may be off? When I added larger wheels I had to multiply my distance by 1.09 to get my actual distance or MPG.

I'll be getting the Superchips programmer then regearing soon. Good luck.

 

Will superchips make much of a difference? I could be "happy" with 12 mpg on 35s but below 10 I would shed a tear

 

I keep hearing good things. I was reluctant with a manual. But everyone sings their praises. I talked to a rep at the Orlando Jeep & Truck show. He was saying you can program for better gas mileage, more power, or a setting for four wheeling. I won't regear until next year. This will be my midpoint step.

 

Superchips will likely not make a difference for your setup, at least until a regear.