With 3-piece wheels (well, BBS RS in my case), I'm sure that you'll have the inner barrel, centre-face and the lips when separated. On the stampings on the centre-face, they mark down the original size of the wheels. I'm just wondering, is this the width of:
1. JUST the inner barrel? Or...
2. the entire wheel, including the original lips?

Specifically, I've got a set of 15"x6.5" 3-piece wheels. I've seen variously sized lips for sale before (advertised as 1.5" lips, 2" lips etc). Does that mean if I fit on a set of 1.5" lips, my overall width would be 8"?
In accordance with reason 1, if the barrel was 6.5", then yes, my wheels will be 8" overall. But, according to my reason 2, if my wheels were originally 6.5" including the lip, then I would need to install a larger-than-1.5" lip to achieve an overall width of 8"? Unless my lips were 0" which I find it hard to imagine. I would go out and measure it if I didn't have tyres wrapped around them.

I guess basically my question is, what depth of the lip would I need to run to achieve an overall width of 8" from 6.5"?

Sorry if the post seems all confusing. I've tried to structure it so it's a bit more understandable haha.