Pretty impressive running 85 averaging 68+ and 18.5 to 20+ mpg. Your truck is right in every way. I may be able to come close to that. I've made 17.2 at 92 and 22+ at 63. I could never drive 55 for a whole tank full, would probably fall asleep. I'm suprised to find out it hasn't dropped below 17.3 with juice on level 4 for a month now. I think my truck thinks its a corvette the way the engine responds, but amazing that the mileage isn't hurt much. My lifetime average for 90,000 miles is still in the high 18's. Great Truck. I've been running the exact same air pressures you have too. However I'm having to back that down now, they're showing wear on the center more than on the sides. Noticed it more on the rears, but I know why.