What is the widest tire we can go on a Stock setup without sticking out / rubbing?

These are the rims I'm looking at getting. I have 2 choices for 18" rim sizes:
18 x 7.5 (42mm offset) with IDK tires
OR
18 x 8.5 (35mm offset) with IDK tires
I'm lowered on HFP, which would work better? I'm leaning towards 18x8.5 with 35mm offset... Thanks in advance!