All the large caps (14" hub caps are 15" diameter) fit ANY of the 14" steel rims.

You will find the car will NOT drive as nicely when you down grade to steel rims because of the unsprung weight you are adding.

If you must fit steel rims,go for the 14" rims from a W126. They have the cooling fins in them for the disc brakes and will help your pads last longer.

My ideal would be to fit 15" alloys from a W201 etc to gain the advantage of better .easier to buy tyres.