I have a BMW 2011 F11 525D M-Sport, I am experiencing vibration at between 60 and 70 mph.
I got my local garage to do a balance on all 4 wheels to start with, but that had no effect what so ever!
I then came across this thread and wanted to say a big thanks to
akroblade954 for pointing me in the right direction and saving me a lot of time and money working out what was wrong!
Using
http://www.balancemycar.co.uk I found 'Discount Tyres Luton', who did a professional job.
They have a Hunter Road Force Balancer and found that all 4 wheels were balanced, but had 'run out' (egg shape) and 'Force Variation' (sidewall stiffness) issues.
I have just bought the car and it had budget tyres fitted.
One of the wheels with was within limits, but the other three were too far out and need to be replaced.
One tyre was the worse tyre that the technician had ever seen, I think it was the 'Force Variation' that was 380lbs out!
He span it up for me on the machine and you could easily see visually that it was way out! The technician said that it should be no more than 80lbs out normally.
To my mind this seems to be more of a problem with manufacturing defects in lower profile tyres, that are not being picked up by just balancing alone!
As you can balance an egg-shaped wheel no problem, but it's going to vibrate the crap out of the car, so I found out!
I think that the car in my case was doing quite a good job keeping it all together until 60mph quite frankly.
I have just ordered a set of 4 x Goodyear Eagle F1 Asymmetric 3 tyres to be fitted in the new year.
So hopefully this will fix the issue for me!