I am wondering if i can use the rims from a w140 S on a W126 S and what the largest width tire size would be ?

Essentially I would like to install 16" rims on a 560SEL and maximize tire width ! What are the relevant constraints ?

Finally, if 16" did not work could I use the inset 15" 8 hole rims (tire size=205/60?) from a 95 C class ?
thanks
farrukh