You need to find the "curb" weight somewhere. The web most likely. The sticker on the door is GVW and is the weight of the truck with a full payload and passengers. Take the Curb weight and add yourself and any passengers, plus whatever is in the truck that is not stock (stereo equp etc..)

Got that from the Gtech manuel. They say GVWR is easier on cars since all you really need to do is subtract the passengers that are'nt there. But trucks are rated with a full payload.

Mike