Interesting payload capacity on my build sheet

[Winterhawk]

I had downloaded my build sheet a couple years ago and happened to look at it today again. It lists max payload at 1800#! From my research normal is 1150#. Mine did come with a trans cooler, HD cooling system, HD suspension, and 225/75r16 tires. I'm guessing because it's a USFS XJ, with the HD suspension and cooling, it has a higher payload. Just curious what others think.

 

[Winterhawk]

Make that 225/75r15 not 16.

Here's an excerpt from the build sheet.

Build To U.S. Mkt. Specifications
Payload Rating - 1800#
Federal Govt Bid - U.S.
Auxiliary Transmission Oil Cooler
Heavy Duty Engine Cooling
Heavy Duty Suspension
Full Size Spare Tire
P225/75R15 OWL Wrangler AT Tires

 

[XJlimitedx99]

That is pretty neat. I've never actually looked at the official payload ratings of these. That is quite the jump. I'm curious which component is the limiting factor that allows a 56% increase. Maybe the leaf springs? Then the cooling systems were beefied up to accommodate.