Here's a set of the AVA Memphis (19's) on a Z4. Looks good, but I think I'd go with 18's, personally.
http://wr6moto.com/2015/05/10/new-car-bmw-z4-3-0i/comment-page-1/#comment-17
http://wr6moto.com/2015/05/10/new-car-bmw-z4-3-0i/comment-page-1/#comment-17


