How would factory 18" wheels be with a lift?

[LRod]

Hi all, I'm new to figuring this stuff out and need some help. So I'm in between either a 4.5" (CST or Rancho) or 6" (Rancho) lift. I have a new 4x4 LD Silverado which is essentially the same as the 2018. It came with the factory 18 wheels and I really like them and would like to keep them on the truck (and I'd be saving money!). The question I have is that since they are not offset they might look weird & I'm worried about how big (width wise) a tire I can put without having to cut anything off to prevent rubbing. I'm trying to lift with the least amount of frame modifications possible.My plan is to go with 33's which should not be an issue. Will a 33x12.5 work or what's the widest that would not rub? 

Is this something normal that some people do, I don't see any pictures of lifted trucks with factory 18's?

I've attached a picture of the type of wheels I have. Thanks for the help,

LRod