Brake caliper clearance isn't really a matter of getting the correct size and offset of the wheel. Yes you need the correct size wheel to fit over it, but the offset will not guarantee that you'll clear the caliper. The caliper clearance is has more to do with the Disk Type of the wheel. Volk calls their disk types: "High", "Mid" and "Low" whereas Work Wheels calls theirs "R Disk", "A Disk" and "O Disk" respectively. .. the disk type with the greatest clearance for brakes is the High or R Disk. .
Low or O Disk gives you maximum lip, with the least amount of brake clearance.