Currently have 275/55 20 tires on our 2011 F150 4x4 3.73 and when it comes time to change, would like to hear any opinions if going to a 275/60 20 will increase hwy mpg by gearing down the back end a little or will it make it worse due to it being a slightly taller tire/ putting the truck a tad higher off the ground. Diameters are stock 31.91 inches and the 60 profile is 32.99 inches.

 

I would guess that going up 1" overall, with your 3.73 gears, wouldn't change your MPG much, if any.
I would be surprised to see + or - .5 mpg.

That is if you stick with the same type of tire also. Sticking with a All Season vs a Mud Terrain tread.

 

I'm running the 305x55x20 Nitto's which are a little over 33 inches tall and 12.5 wide and noticed my mileage dropped about 1 1/2 miles per gallon, mostly in stop and go traffic. I'm still averaging over 16 mpg in combination driving, straight hwy I can get 18 mpg at 65mph. I also had the dealer adjust for the taller tires. A 275x60 may only drop your mpg slightly because this size is usually a P rated tire and lighter then a LT rated tire. Adding weight at all 4 corner's is where you lose mpg's due to starting and stopping. The only thing good about the light *** Pirelli's is that you'll get the most miles per gallon with them on.

 

Wider tires create more drag more drag redeuces your MPG also most people tend to under inflate aftermarket tires creating more drag.. Aggressive tires create more drag. The closer to 5 dollars per gallon we get the more people will pay attention to proper tire care. Check your tires for proper air pressure thats the single most important key. Check them at least once a month as tires loose pressure naturally through the pourus material tires are made of.

 

Nice truck! I was eye ballin your nerf bars on another post, awesome! Currently with 41psi in the scorpions. Ford rec's 35 and the max on the sidewall is 44. Michelin has some nice high mileage tires in the stock 20" size. Kind of like their lattitude's that go on the escape. Probably lower rolling resistance for better mileage. More $$ than the scorpions