It's all about actual pin weight and payload of the truck. Brochures paint a pretty picture. Mine was listed at pin weight of 2,680 lbs. When in rolled in the door, it was 3,400 lbs on the pin, and with water and our equipment it his 4,340 lbs on the pin. The payload on our F350 SRW was 3,750, so even without water we were bouncing off the maximum which is not a good feeling, especially on tires that are maxed out.
The F350 dually has a payload over 5,500 lbs, tire capacity of nearly 12,000 lbs, and a 9,000 lb axle so it handles our 4,340 pin weight and 17220 gross weight of the trailer nicely. Didn't want a dually, but it does what it is supposed to do.