We always use weights, because "figuring it" and seeing it are totally different. Yes you can find your objective over pressure, but did you actually see the car run at full load?
Good example, added a new elevator in an existing hospital wing. Both cars ran on the same generator, inspector required I run both cars on gen 100% capacity. Needless to say the older car could not take full capacity, even though the logs had been checked off for the over pressure setting. I imagine the tech had used existing numbers, hit the shutoff and run the car to verify he was close, and moved on....
