Yep, been looking at that gap, on my a3 I can get my wheel brush in there but I doubt it will on the a4. Still there's always my wheel woolie http://www.theultimatefinish.co.uk/...eh_vK_j2XVgkLhPBY0rp3uUOiVHWwpEiJEaAj8O8P8HAQThey are big, but I'm not sure about the pic as mine look even bigger than them! (Could just be the angle)
I've got the 19" and there is barely any gap between calipers and allloys. (Makes cleaning inside alloys a nightmare!)
Somebody has already posted on here that they are R8 calipers (same part number!)