bill, i am not trying to be argumentative, and i am not trying to dump on your wheels.
my friend has a late late 320 18v 129sl, with 18" amg alloys on it, they are stamped '///amg' and they appear to be exactly the same as yours.
he has had them refurbished, and when they were removed, the refurbisher told him they were one piece.
now i must admit yours look like two piece alloys from the pictures, and, when i asked him, he said his did as well, when viewed from the front. i have not seen his when removed either, and am going on his infromation.
he says his deffinatly looked two piece, even down to apparently chrome bolts like yours. (he had them refurbed all one colour by the way!)
so, if you were to try to remove a bolt, and it came out, then they are indeed two piece.
if
you dont want to take one out, in case it marks them or make them leak, then you could take a wheel off and look from the back, andy says his were clearly not two piece when viewed that way, the ridge you can see at the front that is painted two coulours to exaggerate it does not, according to him, feature on the back of his alloys.
so either
yours are different wheels from his apparently identical ones, and amg made some one piece and some two piece 18" alloys of that design.
or
he is wrong and his are two piece, and the refurbisher gave him incorrect information, and he must have not 'seen' the ridge on the back of his alloys (there must indeed be one on his 'two piece' amg alloys)
or
yours will turn out to be one piece...
i dont mind, as i have datsun wheels on my 124, and would not use any of the over weight, over priced and all to common amg alloys, i had carlsson three piece 18" on mine for a while, but they were also well heavy.
i have discovered light wheels make much improved performance.