Go HOGS ! Beat L.S.U.
Wish I could help more , I have a 2014 4X4 QC 6 speed w/ 3.55 gear ratio , stock tires and leveled with Bilstein shocks.
I get 19.5 - 20.5 all around driving and up to 23 mpg on long interstate driving . I drive like an old man ! Light footed !
I'd say leveled with medium weight 33" tires & wheels , 5.7L with the 8 speed with 3.21 Gear ratio = 19-22 mpg all around 24 mpg interstate.
With 3.92 Gears 20- 23 mpg all around and 25+ interstate .
This is with my driving style , your right foot may be heavier or lighter than mine .
You will get more responses in Engine & Performance thread .
Or Lifted thread .
Be prepared to get bashed on being concerned about GAS Mileage driving a 4x4 tank ! LOL
The 8.speed xsmn is geared lower in 1rst &2nd gear , thus giving you an advantage on heavier / bigger tire selection .
If I had the 8 speed I would still prefer the 3.92 rear end G.R. and I'd go 35" tires on a level .
Welcome to the Forum HOGFAN32 !
Hope this helps !