I looked over the threads in this forum and didn't see anything like what I am experiencing with my car. Soooo...here is what I observe and what I am doing about it.
I purchased the car used with 16000 miles. Certified BMW. After 5k or so highway miles I noticed a pulstating noise while driving which seemed to come from underneath the vehicle. I checked the runflats with my son who is a mechanic and he noticed scalloping on the outside edge of the tires. I read up on this an others have had a similar problem. So I decided to purchase a new set of tires (not runflats) and have them mounted and balanced. I thought the problem was corrected but recently I noticed rhythmic pulsating noise again. This noise is different from before. I checked the tire pressure and wear after 12000 miles and the tires look great (Kumho Ecstas). I don't believe the noise is tire noise.
To test my theory I took the car up to the high school parking lot and made a series of slow (10 mph) tight turns in the left and right hand directions. While turning left I hear a distinct rhythmic groaning/grating noise. While traveling straight, starting at about 20 mph I heard the same noise. Not so much when turning to the right. The noise is coming from the rear of the car and I'm leaning towards a bearing or CV joint that is or has gone bad. What are the collective thoughts of this forum?
Thanks for listening.