I have same problem on 2007 335i
For last 6-9 months My ride is getting Choppy or grinding or humming whatever you called. I have Continental ExtremeContact DWS and I think I had ~30K on them. Took it to the BMW Dealer and he told me Tires are worn out uneven but thread is not bad. They did replace the Front Ball Bearings since they found that its going Bad but the noise never went away.
I think my Continental DWS are not good after 25K and wear out uneven, and become very noisy, but they are good in Wet traction and Snow. I really need a Tire which is quite so no more DWS.
But it may be other issue as many mention which cause the Front tire to go bad, like joints or Arms or Toe..