Are 16.5 wheels 16.0 or 16.5 inches?

[davepl]

My Longhorn has 9x16.5 tires (nothing listed on the SPID though), and I know this sounds like a dumb question I could just go out and measure, but I don't know if they measure from outer edge or inside the bead, so:

Are 16.5 tires what you'd normally refer to as 16" wheels, or are they literally 16.5?

I wanna slap some 22" dubs with spinners on this and when I sell the old ones, I need to know what they're called. Thanks!

- Dave

PS: Just kidding about the dubs. Figured I'd give Jesse a heart attack if he's reading along. But I really do want to know what the heck these wheels are.