I have a 2019 GMC Sierra 1500 Denali with 20x10 Fuel Mavericks with a -18 offset on 33x12.5x20 tires.
Looking at other builds on the same truck with similar wheel/tire combos it said they didn't use spacers.
When i had my wheels installed it wouldn't fit becuase of the brake calipers. I ended up having to use spacers, needless to say I was a little bummed.
What I don't understand is how these other same trucks got away without using spacers on similar wheels and offsets.