I was thinking about changing my tires and i was wondering how much it would change my mpg. i have the 5.4 and 3.55 gears and want to run 285 75r16 bfg atkos. let me know what your mpg are if you have this same set up.

 

I DON'T have that setup, but I'm glad I didn't do it!! I got some 265/75/16's (31" tall) and I could tell a difference...... I have re-calibrated my VSS gear, so my speedo/odo are back to normal and my trans shifts like it did before.....

You are talking about a 33" tall tire and while it's dooable for a totally stock setup, you will notice a bit of a 'bog' off the line and some mpg loss... Mostly due to the fact that the 33" tall tire weighs more, has more drag and is taller, so it lowers your effective gear ratio..... With 3.55's, it's gonna be like you have 3.08's in there with the 33's....

JMO....

Mitch