I wonder which set of wheels (original 14", 15", 16"?!) and tires would offer the best ride quality for a W126 500 Sel machine?

Now I'm having a set of 15" BBS wheels with 225/65 R15 tires on it and the ride quality is far from what I would expect from such a car. I consider getting 195/70 R15 tires or even switching to original 205/70 R14 tires and wheels to improve it.

I will always choose the ride quality and comfort of a "true Benz" over "looks" and a poor ride.