W124 High Speed Vibration

[tombance]

I have a 1991 W124 car that has a slight vibration coming through the steering wheel and in fact whole chassis when I go over about 75. All I've done to alleviate this so far is to tighten up the steering box, which made the steering much better, but didnt affect this all. Some key points:

- For some reason one of my wheels has a different offset to all of the others, the different offset wheel is on the front.
- I have some new but very cheap tyres, but I had the same problem with my old ones so dont expect balance issues. The new Tyres were fitted and balanced (I saw it being done).
- The car has 130k miles, and I dont think any work as ever been done to the suspension except new shocks all around.

So any suggestions on what could cause this before I start replacing things randomly. Would the steering damper affect this?