Is anyone running the 275/70/18 tires that are stock on the F-250/350? They measure 33.2" tall, so 1.8" taller than the 31.4" tall stockers, but are only .3" wider.

I was thinking the extra height would help my highway fuel economy (I run at 75 mph, 2150 RPM) without being wide enough to harm economy. Nitto's web site is showing 625 revolutions per mile on the 275/70/18 Dura grapplers vs 658 revolutions per mile on the stockers. That calculates to 2042 RPM at 75 mph for my truck. Tire weight differences are pretty small, 51 LB for the stockers, 55 lb for the 275/70/18.

For wheels I was looking at the XD795 Hoss in a 18x9 with a +30mm offset, 6.18" backspacing. The backspacing is about the same as stock with an inch wider wheel, so the tire should move out half the distance or .5 inch. I'd rather find a 18x8" wheel with the factory offset, but I don't think that's likely. I can't imagine the weight differences between the stock 17" aluminum and the XD's would be much.

My other option would be a 285/70/17 tire, but I don't want the extra width to negatively impact my MPG. Going from the stock P265/70/18 to a LT285/70/17 cost me 2mpg on my old gasser.

Pep Boys is running a buy 3 get 1 free promo on tires, I was going to see if they'd honor it on a set of Dura Grapplers. I'd have to buy their road hazard, but it'd probably still save me $100 on a $246 tire.