Murano vs stock rim weight
 

I swapped my wheels back to the stock ones, so i figured it might as well get a quick measurement of weight. The stock rim has the Continental Contiextreme Contacts 225/50/16 while the Murano rims have General Exclaim UHP at 225/40/18.
I basically used a bathroom scale that I stepped on first. Then I held each wheel while getting back on the scale.

The results are:

Stock rim with tire: 44lb
Murano rim with tire: 47lb.