Front Rubbing - Tires, Suspension or Wheels?

I assume that it is, but I just thought it was interesting that it was listed under the offset.

So, if I want to match the placement of the current wheel (15x10 5" bs with 1/2" offset) with the narrower 18x9.5, then the 5.25 backspacing with 0 offset would be correct - right?