How much 'margin' did Toyota leave in the GVWR numbers?

So I looked at my doorjamb sticker:
(2021 SR5 Crewmax)
- GVWR: 7200 lbs
- GAWR Front: 4000 lbs
- GAWR Rear: 4150 lbs
- Payload: 1270 lbs

Seems like I would have a 'real' weight capacity of 4000+4150=8150 lbs

What happened to the other 950lbs that aren't included in the GVWR?

There's also a yellow sticker that says "Modifications to this vehicle have reduced the original load carrying capacity by 70kg or 154 lbs." I got the TSS package which includes steps and 20" allows, Goodyear Duratracs. Also factory spray-in bedliner.

I don't see how wheels & tires would factor into the GAWR ratings at all since they don't push down on the axles at all, therefore I can ignore them. The steps & bedliner, yes.

 

I believe their publish ratings are very conservative, but I don't know by how much.

 

Axles aren't the only thing that is used to calculate GVWR. Wheels, tires, suspension, frame. You have narrow leaf springs in a Tundra for one thing.

 

Your add ons do not affect the GVWR at all. They affect your payload. The GVWR never changes.