You'd need spacers for the Avus really, to drop the ET to 35 or so. With the exception of the S-Line's the S4 was the only A4 with 18" wheels as standard. I don't know any stats for the Star style 17's, but the Trapez style 16's with ET43 are probably only a 7.5j so will sit similar in the arch to the 8j Avus's at ET45.