My 1994 C180 is having vibrations now and this is in the steering wheel when driving mostly at higher speeds like 80kph and above. At idle and in auto gear, it also vibrates, but in N it does not vibrate. The floor boards also vibrate and so do the seat bottoms. Why? Is this due to the tyres, shocks or coils? The tyres are newish, lots of tread, I use only weekends. They were put in by a sus dealer to clear the inspection. The tyres are Simes from Malaysia, virtually unknown here. Very deep treads, nice looking 195s, but have very hard sides and so maybe the ride too. May be uneven wear or tyres are square, not truly round? Maybe the engine mounts? These will cause vibrations whether in drive or N. Mine is ok in N, so maybe mounts are not there yet. What do you guys say? Mileage is 194,000kms round Venus and back!