I am trying to adapt a modern steel wheel on the 409 as I cannot find a good set of the original wheels (manufactured, I gather, by Dunlop.) This Mercedes-Benz wheel is nice, sturdy but it's a 6"x16 whilst the 409 wheel is 5"x16. The 'crown' where I would have to install the posts that would keep the hub caps in place has a diameter of 9 3/4 inches