i have a 2007 lariat 5.4L supercrew 2x4. i have recently put on a slightly larger tire and 2.5'' leveling kit. i went from 265 to a 285 tire. my gas mileage has decreased sustantially from 380mpg a tank to 300mpg per tank on a good tank. is this because of the difference in tire size or something mechanical? do i need to recalibrate the odometer for the tire size? also i have about 30k miles on my truck and have not given it a tune up yet. someone told me that if i change the fuel filter and put new plugs in that it will correct that. is this true?

 

If you put bigger tires on the truck, it will decrease your gas mileage. One, because of the taller tire and two, the taller tire has thrown off your odometer. It was set from the factory for the original tire size. Same thing happened to me. You can buy a tuner with the setting to change your tire size or you might be able to take to the dealership and have them do it. Good Luck