You have to check the weights of the wheels AND the tires when you shop around because they vary all over the place. Most companies will list it for you.
I weigh all my stuff just because I'm a bit finatical that way.
The factory 16.5 steel wheels on my 1 ton, along with a stock size 9.5x16.5 Firestone 10 ply tire that I run, weigh 70 lbs. a piece!!! That's an extremely heavy wheel/tire combo. These factory steel wheels are so thick that your standard wheel weights won't simply tap onto the lip of the wheel. These are stout wheels for a steel rim.
I could put just about any aluminum wheel on this truck and probably save 10 lbs per wheel,,,,that's a huge savings in unsprung weight
Not just for gas mileage and accelerations purposes, but lighter wheels also help braking as well. Just something to think about....
I had even contemplated going with the factory GM forged aluminum wheels found on the 3/4 tons circa 2001-2005's to save some weight and at the same time I'd have a 16" wheel with more tire choices (gets rid of 2 problems at once). But I just can't get over the look of the modern wheels on an older truck.