Regarding tire pressure, I gained 1-1.5 mpg by running 60 psi front and 50 rear. I am not advocating everyone do what I am experimenting with as this is a trial run and you do what you want. My theory is that the door suggestion is a recondition based upon several factors. Type/brand of tire may come into play, the sticker recommendations are a compromise as it is to give decent wear, be safe and a decent ride. I have always found on just about every vehicle I have ever owned in my almost 40 years of driving that the sticker is on the low side. The last thing manufacturers want your impression to be is..... This thing rides like a tank. Of course higher pressures ( within reason) will ride rougher. You need to find out what your contact patch is and a good way to determine that is to use a wide chalk stick and run it across wash tire. Then drive a short distance and see where the chalk wears off. Only in the middle gives the indication of over inflated tires. As long as you are not running on the center of the tire and the patch across is being utilized, at least that is a good indicator that you throw into the equation. Never exceed the tire reconditions posted on the tire but they are normally much higher than your sticker numbers will be. Payload and useage varies which is another factor that needs to be considered. I am not running the stock tires so I do not know how they would react to my current pressures as I have Nitto 305/70/17's. Again, I am not telling everyone to run out there and run stupid pressures and that is not the point. I wanted to pass along my experience so far as I am also disappointed in the mileage. I had a 2014 Ram 2WD and got 23 on the highway with the same engine but it did have 3.21 gears. The Rebel is a lot heavier but I personally feel a lot of the issue is the tire pressure. i have not noticed an uncomfortable ride at 60 front and 50 rear and saw 16.9 yesterday combined driving for the first time compared to my average of 14.5 to 15.5 for the same driving. Here in Texas, the speeds are up to 75 which we all know kills mpg. as well. Just my 2 cents as to what I am trying.