put 2" front and rear lift spacers on my 2008 burb. Looking for the most aggressive wheel fitment without scrubbing.

Somebody tell me if my research is right:

-could go 0 offset (5" backspace) on a 20x9 and stick to stock ~32" tire
-or go w/ 15 to 18 offset (5.5-5.75" backspace) on a 20x9 and be able to go 33" tire

bottom line I could have the aggressive 0 offset but bound to stock size tire. If I want big tire I need to keep the offset closer to stock?

Any advice is appreciated. I've read for hours and everyone has different opinions, so I'm just asking now!
Thanks,