I apologize if this seems rude, I am not trying to be.
I am really curious, why do you want to know what the wheels gross weight is?
not all 16 inch wheels are the same. I don't know anybody in the automotive industry that goes around weighing random rims.
I bought a set of used 16 inch, with the correct bolt pattern, and they were not even close to fitting. this was regarding the inner diameter, and clearance of the calipers.
you can figure this quandary out with math, and research.
search your exact tire brand/model/size… You can figure out exactly what this tire weighs by looking at the specs, or by adding one to your shipping cart and going through all the processes… It will tell you what the shipping weight is.
search your year make and model replacement rim on eBay, and see what the shipping weight is. Subtract and you have your answer.
A question like this seems to be wasting good friends time, why can't you do a little homework for yourself?