Those wheels were Replicas – ASA Type 8, and had the right offset for the W126. You can’t take W124 or W140 wheels and put them on a W126. They will bolt up but the offset is all wrong. Where I live in NSW Australia, spacers make your car unroadworthy unless factory fitted or engineered. (i.e. a government certified engineer gives you a certificate which is quite costly).

While they were 16s, because I had lower profile tyres, the rolling radius of the tyre was within a few percent, so I was able to maintain the factory ride height and the speedo was as accurate as any W126.