GVWR is a combination of the 'whole' NOT a 'sum' of the components.
GVWR takes in to account the frame strength, axle ratings, suspension, wheels and tires.
Payload is GVWR Minus UVW.......then one has to subtract weight of people, stuff, accessories, stuff to determine 'actual available' payload.
Air bags, Timbrens, add-ons etc. do NOT change/increase GVWR or payload.
One either accepts and complies with mfg. ratings or justifies going over them.
Typically wheels/tires are the weakest link in the 'ratings' numbers
