I think there's something wrong w/ gas guage???
 

Now I know that I didn't buy this truck for the superb gas milage. And I"m sure I didn't help after putting on 35/12.5 MT's on stock rims. But I calculated my gas milage the other day and I came out to 9.4 mpg. THere's a guy at work that has a 97 chevy (we bicker back and forth, but he likes it), that has 16 inches of lift and 40 something inch tires and he's getting about 9mpg. I have a K&N air filter that's brand new and I'm not heavy on the gas or the brakes. I do all city driving, but I'm not a hard driver at all. ANy suggestions or possible solutions?

Bigger tires affect the Speedo which affects the odo. You will be seeing less miles driven per actual mile driven, thus performing calculations with lower miles. for example I went from a Mickey Thompson 33 x 12.5R17, to a 295 70 R 17 Nitto Terra Grappler and my speedo reads about 2mph off (lower) at every speed (checked against GPS). The tire size difference in diameter is from 32.8 to 33.19, less than 1/2 inch. If you went from stock to 35s, you will see a bigger difference. So, that's one thing. Also, you shouldn't use gauge position to calculate mileage, but the numbers on the pump...

P.S. Love the yellow!
https://www.f150online.com/galleries...llery10991.jpg