I notice that 65 MPH vs. 75 MPH highway driving gives me most noticeable difference in MPG.

I typically get 12-13 MPG with the 35" tires. I can get up to 16 MPG on highways going 65 MPH.

The best MPG I ever recorded:
- October 2010
- Weather was cold/snowy
- Roads were mountain highways driving between 55-65 MPH
- I had TOD ON with hubs unlocked (until I spun out in the snow)
- Running 32" BFG mud terrians
- Roof Rack equipped
- VX went 405 miles on one tank, I filled up the tank with just over 20 gallons of gas and calculated 19.8 MPG.