I found this in another forum: Seems like this is VERY common and normal for the F10 5-series.
Dampen Vibrations at highway speeds - Pretty much the only real criticism I have of the car is that the ride at highway speeds (70-80mph) turns subtle road wallow into more rhythmic vibration at the seat and steering-wheel than I would prefer. It happens in all suspension settings. It's reminiscent of the feeling of unbalanced tires, but it's much more subtle. My five-year-old S5 doesn't have any such sensation on the same patches of freeway, so clearly it could be improved. However, I felt the same thing in my friend's older 750 recently, so I don't think it's anything 'wrong'. Like most involved in the forums, I'm very tuned to every little sensation in the car. It's hard to say how much of it is caused by the Goodyear LS2 RFTs, vs RFTs in general, vs the car design (intending to transmit road-feel). Maybe someday I'll put some non-RFT Pilot Sports on it and find out.
I have been battling this sensation for 1 year now on my 535i xdrive and I cannot understand why it still does it after trying 3 sets of different tire brands, rebalancing several times and settling with the Michelins Pilot Sport A/s which does have a very smooth ride but on most highways 70-80 there is back to forth subtle vibration sensation in the front seats and it annoys me a bit hat I have been trying to seek out the cause for it and drove other 5 series and they mostly all do it. However, the Michelins do make the car more smoother and comfortable other than that small vibration zone. My 335 xi coupe does not do this at all no matter what highways at all speed. So its baffling. My Audi A8L is much more planted also. it seems that this 5 series "soft" suspension develops a funky harmonic around this speed of 70-75 and gets bumpy no matter how perfect the tire/wheel balance is.
2013 F10 BMW 535i Alpine White / Oyster Dakota Leather / Anthracite Wood Trim / Steptronic transmission / M Sport Package / Premium Package / Technology Package / Rear-view camera / Park Distance Control