I have a similar truck, except a 4 door with the 275/70/17 tires.

The overhead readout is consistently 1 to 1.5 mpg optimistic. I hand calculate each fill up. It averages 10 mpg locally and 14.5-15.6, depending on the road (60-70 mph)

The odometer is pretty close, so the problem is in the algorithm they are programmed with.

I have been resetting the readout the last few times I fill and it is within .1-.2 mpg for me figuring by hand.

I read the article on the Michelins, I don't mind paying a little more for tires but have heard some iffy reviews on them also. My Mickeys were not cheap either, probably around same $$$.