Although people think that the rondell's are 18" replica's of the 8 hole but I personally think they are more like the 15" "Deneb" wheel from the prefacelift W202 which may have been made by rondell for Mercedes in the first place as they are a OEM manufacturer.
They are Rial wheels...I have a set in 7.5 x 16 which I hope to use on a 190e project at some point. There was a chap on here selling the 18 inch version but it was some time ago.