For starters the manufacturers all deduct 150 lbs per passenger seat with a truck. That is why the highest payload capacity is always for the regular cab trucks. The payload is also a calculated rating based on how the truck was configured when it left the factory. Often the wheels and tires are the limiting factor and my 2011 2500HD had a greater factory payload rating at 2800 lbs than most of the 3500 trucks on the dealer lots.Just about pulled the trigger on a 2020 high country 2500 and trade my 2015 LTZ 2500. Never thought to look up the payload, its a 2020 bigger, stronger more torque, tow more all the number are better right? Good thing I checked the sticker inside the door, the 2020 payload was a useless 1500lbs, my 2015 is 2200lbs , the same as my fifth wheel pin weight, both trucks loaded and same gvwr , obviously the 2020 needs to go on a diet . All I can figure is the larger cab on the 2020 sucks up 700lbs of payload. Anyone run into this?
The axles are rated at 11,000 lbs and the same ones are use on the 2500 and 3500 trucks. What is different is the leaf springs and the wheels and the tires. I swapped out the factory tires for Nitto ones and gained 1100 lbs of payload capacity at the rear axle. I added a double leaf set of SuperSprings and gained another 1400 lbs of load capacity. With a 4000 lb load in the bed the truck sits dead level and there is no sway in the curves.
I could gain even more payload capacity if I was willing to spend $3500 on a set of 19.5 wheels and tires for the truck but it is not really needed.