Original post by: Dave ,
I get bad fuel mileage pulling a Conestoga, I have a mid-roof so the direct impact of the wind hitting the bulkhead of the trailer drives it down for me. With a flat, same principal applies, taller the load, worse it is or if there's an object on the rear that's taller than the part of the load in front of it the worse it is. If I have an A/C unit on, I load it as far forward as I can and slide my 5th wheel ahead as far as I can to eliminate the gap. Not every trailer pulls the same, might be worth jacking it up and just see how much effort it takes to turn the tires in the air. Maybe there's one hub that's noticeably not rolling as well?