4 inch fabtech lift in a 2015 silverado, will 17x9s with a -12 offset

[Vonderosa7]

I have a 2015 silverado that I had just put a 4 inch lift on from fabtech. I have 17x9s right now with 33x12.5s on but I can't figure out what offset they are. Either 0 or +18 but they hit on my upper control arms full turn both ways even with a quarter inch spacer. Wondering if going with a -12 offset and would do the trick