Any ideas for the cause of steering wheel vibration?

[Eurohooner]

Coming back from Germany earlier this month the car developed a fine vibration at 75-90mph. Not too bad and this weekend I dropped it in to my local tyre fitter for a track check and balance. Tracking OK, said wheels were 'way out' of balance and corrected them.
Yesterday on the M6 Toll the car was almost terrible due to the amount of vibration through the wheel between 70 and 90mph. Car back with tyre place today. I trust them and have used them many times due to excellent service. They are re-checking the fronts (although they feel sure they will be right) and taking of the backs to check them and a complete wheel and tyre check.
If this doesn't come up with anything has anyone got any suggestion? Car still in warranty. Vibration is bad enough not to want to drive on the motorways until corrected.

 

[aquazi]

if the vibration is that bad and speed related it has to be the wheels...

Either one of the front is buckled; or you have a flat spot in your tyres.

 

[glastoveteran]

I had really bad vibration on my Z4MC at those speeds when I bought it from BMW as an AUC. It's now completely solved after they have done the following, so it could be any of these in your case:

replaced dodgy wheel bearing
replaced a buckled wheel
balanced all 4 wheels
sorted alignment / tracking
replaced front brake discs which were warped

 

[Eurohooner]

Thanks. FRnot brakes were replaced under warranty a couple of thousand miles ago so that's one less to consider and it will be tracked and balanced again today. My worry is a buckled wheel. Are they easy to spot?

 

[MRol]

Balance the front wheels

 

[Eurohooner]

Fronts have been rebalanced and the rears balanced (and taken what seems to be a lot of weights) and car much better. Near side tyres have a flat spot (I think it was a particularly brown trouser moment at the Ring the other week ) but not so bad as to need replacing in the view of my fitter. Will see how it goes over the next few hundred miles or so.

 

[glastoveteran]

My worry is a buckled wheel. Are they easy to spot?

As far as I know the only way of checking is either on a balancing machine, or standing the wheels face to face and checking for gaps, but that's not a option with tyres on them sadly!