[Longshot270]

I went from a 235/70-17 street tire to 265/70-17 cooper atr's and I had a slight increase in mileage. It all depends on how you use it. I recommend a vacuum guage so you can keep tabs on your driving. It will probably give you more mileage than any other mod you can do because instead of modifying some aspect of the truck it modifies some aspect of you.