65 Plate S 500 (C217) Harsh Suspension Help !!

[kerry11]

Hi,
Can anyone help, I purchased a 65 plate S500 in December from a Mercedes dealer and I am very unhappy about the ride quality, it seems very harsh over any road repairs and slight bumps and a fair bit of road noise through the car, also at around 70-80 mph there is a noticeable vibration/resonance through the car, like a propshaft out of balance or flat spotted tyre, the back parcel shelf vibrates slightly along with the passenger seat.
I mentioned it to Mercedes when it was in the other day and their mechanic confirmed the vibration in a test drive but said the ride quality was ok but I know its not.
Mercedes said I should try changing the tyres which I will but has anyone got any ideas, can anything cause the airmatic suspension to become harsh without sagging.
The car is on 20" wheels with normal tyres not run flats, but my previous CL500 had 20" wheels on but the ride was perfect.

[Dunit]

You might want to check you have not got a dented wheel rim, Check the inner edge which is where they go.

[kerry11]

Thanks, I'll get them checked tomorrow, and if ok then change the tyres.