Ok I dumped my silverado z71 crew, nicely modded n picked up a leftover 13' ecoboost FX4 Screw. 3.55 rears. I been reading forums for a week and am at mental overload. Im gonna do a cai n tune, maybe MPT. I need a E-rated tire because of work. I want toyo a/t2's, had bfg a/t's. They're great, not so much in any mud n i want some better rolling resistance. So it seems a 275/65/20 is most common with ppl crying abt mpg. Also noticed alot of guys have the 3.73 gears. Im wondering if the 285/55/20 will b better for not keeping the truck in boost, but its 2lbs heavier than the 34's, so i have the UNSPRUNG weight issue. Any tuned guys with 3.55's that can chime in? I know i gotta pay(mpg) to play, but i drive alot of highway n can rack up 25k mile/yr too.....