b6 s4 avus fit our car? 18x8 et45 5x112 with tires 235/40/18
 

thinking of getting them from germany if they definitely fit

Yes ... exact fitment

are you sure? cause this guy in germany isnt sure.. and says it mite be too big!

It's gonna be 6mm closer to the suspension
 

Probably too close. If the offset (ET45) is the same and the rim is a half-inch wider (B6=8", B5=7.5"), then half the extra width goes on each side of center. So, it'll be a quarter-inch (6.35mm) clser to the suspension, and it'll fill the wheel well an additional quarter-inch. That's why most 8" wheels for the B5 S4 are ET35, roughly.

Of course, I could be wrong-
-df

Based on the fitment of my 235/40-18 S-03's on 18x8 ET35, they would not fit 10mm closer in.
 

With non-S-03's it would be too close to tell without doing a custom fit for each tire (235 S-03's are really about a 240 in width). Then there's brake caliper clearance which is another separate issue.

Oops ... you're correct (math), didn't think about the 8 v 7.5 issue
 

I was just looking at the fitment and tire width, but overlooking the fact Avus III are 8" wide.