How to measure a wheel
 

I dove into this after discovering by initially word of mouth I can't reinstall the 15 x 8 GM rally truck wheels I've had for ages. Good thing I didn't have them refinished, and new tires too, was preparing for it. Dog gone it, I was 50/50 on having dropped it 4/2.5, and after learning that, well I'll just live with it. Not cutting control arms and such....I seem to be on the hunt for 15 x 7 GM now, more or less.

This got me interested to know more about measuring a wheel. There's a TON of information on how, lots of it wrong, some confusion, and some good stuff too. So to understand it better with one picture, I threw this together; boy, I need a hobby retirement is rough;) Please tell me if you see something wrong or needs clarification. Sorry it's so big here, the attachment was too small to read.

I see where some measure a "lip" someplace of 1" or so on these wheels, where might that lip be and why is it important, anyone?

https://scontent-sjc6-1.xx.fbcdn.net...IA&oe=6890B413

Bolt pattern, Height, Width, Backspace and Offset