My $.02, I wouldn't think tire weight would affect payload in any significant way. They are unsprung weight, meaning the is no affect on the suspension, frame, or any other load bearing components. Imagine the tires weigh 500 lbs more than stock, the truck wouldn't sit any differently. As stated above, your GCVW would decrease bu the weight difference, but payload should remain unchanged. Maybe I'm not looking at this the right way?

 

There is no true "payload" rating. There is only a GVWR, GCWR, GAWR. And all those are measured from beneath the tires. So tires and wheels are included.

What is on the Yellow sticker is a calculated number based on the factory curb weight subtracted from the GVWR. It's an approximate guideline. If one is wanting to know true payload capacity, visit a scale and subtract the truck weight from GVWR.