I'd be willing to bet it's the offset of your wheels. I don't see s-techs lowering a car enough that you'd need more than -1.5* of camber to clear anything, so wheel width, tire size, and wheel offset are the three things that come to mind.

Given that you've been here long enough to know what you're doing, I'd say you probably have the correct tire size, and wheel widths really don't come into play unless you're pushing past 7.5" wide, so offset is the most likely cause of the rubbing. Like addiction said, roll your fender lips and you should be fine.