I was wondering how many people are running 285/70/17 vs 315/70/17 tires on their trucks and if there is a noticable fuel mileage difference?

 

going from 33's to 35's made my highway rpm's much better, with my g56 and 3.73's. my mpg dropped by less than .5, but it was just before winter, so winter fuel and driving in 4wd probably accounted for some of the drop.

 

I went to the 285/75/R17, and the RPMs now feel right with the G56. I also went to mud tires (Toyo OC MT). I do not have enough miles on the combo to report mileage, but it feels like it is about the same. The truck is definitely pleasanter at highway speeds. I now cruise below 2000 RPM at 65 MPH (corrected), and I no longer try to shift into 7th gear.

 

..... couldn't agree more.