Well, its time for new tires and I am back to driving the truck daily, so mileage is very important. I have 285's now, and do go off road, therefore wanting to keep the 33" tire. What effects the mileage more, the height or the width/added weight. Mileage is most important at this point, but if the 255's will be close I would definitely go with them. Thanks

I think your mileage would drop some hwy and a bit more in the city with 255s. That is what I have and I didn't lose any MPG hwy but I think the city is down. Since you have a gasser I think you would suffer more. If your a member on FSC there is a guy there with BFG km2s 255s and a 6.0. Rebel something is his name.