I recently regeared to 5.13's and I'm running 37 trail graps.
-Before lift and gears we were averaging 15.5mpg with 32's and 4.10's.
- After lift and tires we were getting 11.5mpg.
-So then regeared to 5.13 and used the Procal and it started showing 17.9 and has decreased to 13.3.

Maybe it's just me but I was figuring with the gearing and Procal that we would end up back around the stock mpg range. Anyone else seeing same results.
Again I'm only curious about those running 37's.

 

I would say not a chance as the 37's are so much heavier regardless what the gearing.

 

You're also increasing the front area of the tire thats pushing against the wind by quite a lot.

 

There is also a big hit on millage with air drafting up under the Jeep. This is a huge hit on millage actual..

Have you seen the winged sides they are putting under transport trailers these days? Those little panels are saving them tonnes of money in gas by reducing the air hitting the bottom of the trailers.

Re-gearing will get you better millage but only better not excellent.

 

I have 4.11's and Toyo 37's. around town, 13.5; on highway going 75; 12.8 with ProCal

 

I have 35's and once I put my front bumper and winch on the mileage dropped to 13.5. The bumper is a LoD Armor Light (33 lbs) and with the winch probably weighs a little under 100 lbs. In my case, I suspect the turbulence under my Jeep is causing the issue. I'm thinking about slapping my factory 'skid/air dam' on over the skid plate to see if it helps.

 

Why do you think you'll get same mpg as stock? That makes no sense.

 

I get about 15mpg highway and around probably closer to 12mpg city with 37's and 5.13 on mine; so that sounds about right to me.

 

It can happen.Driving habits help play this out.With our gearing and 35" we had better than stock fuel mileage

 

How recent were the changes? The change over to winter grade fuel and longer warm-up times (for those of us in the colder climates) takes a chunk out of mpg also. I've seen a 2.5mpg (hand calculated) drop in my stock JKU since the fuel changed over.