Tyres.co.uk lists the Michelin XVS in 185 HR15 and the Vredestein Sprint Classic in 185/80 VR15 for the Mercedes 220 W187. These products are suitable for the 185 R15 front and rear fittings allowed by Mercedes-Benz. Please check the specifications of the wheel, tyre construction, load and speed ratings against the records of the original vehicle prior to ordering.
Mercedes 220 W187 does not have a contemporary tyre information placard on the door jamb or fuel flap. Factory reference is the owner's manual, so check the handbook and sidewall markings of the tyres, then check the specification against the original wheel fitment of the car before ordering.
Typically, all four tyres don't need to be replaced on a Mercedes 220. The Mercedes 220 W187 is rear-wheel drive which means there is no four-wheel-drive version, but do replace tyres in pairs on the same axle where possible. If you are replacing two tyres, then UK safety guidance states that you should put them on the rear axle.