Humming Noise in my 2004 M3 Convertible (SOLVED!)

Hello,

I have a humming noise that is hard to tell apart between tire road noise and possibly wheel bearings. I can also feel a high frequency vibration in the steering wheel and brake/gas pedals....although this is very very faint.....not very noticeable. Also, the noise is non-directional so I can't pinpoint where it is coming from. I read the posts on wheel bearings and jacked the car up, vigorously shook each wheel only to find there was absolutely no play in the bearings. My tires have about 30-35% tread left on them, and the car has 42K miles. This started almost overnight at around 41K miles and hasn't changed. The noise happens only above 15+ MPH and changes in pitch slightly until about 50+ MPH and remains constant after that. Changing gears doesn't change the sound (SMG transmission).

I'm hoping someone can give me a good order of things to check so I can find the cause asap. I have the following questions to start with:
1. Even though there was no play in the bearings, could they still be the cause?
2. I've heard the rear end (ie. transfer case, axle, etc) on these cars was prone to having issues, I hope this isn't the case but how can I check that?
3. I may have to just wait until I buy tires to rule those out (which will be in several months), has anyone had their tires cause this?
4. Any other ideas to consider?

Thanks for any and all info.

BMW gave me a motor mounts problem after the same type of noise was reported to them. 500ish to fix.

Thanks for the tip! I'll be changing the oil this weekend so while I'm working on the car I'm going to check this out as well as take a very close look at the area around the wheels. I also plan to jack up the back so the tires are off the ground and run it so the back wheels spin and see if I can either rule out the back of the car (or narrow it down to the back end [other than tire road noise]). I'll post my results as I get them.

After starting at the ground and working up I eventually found that it was indeed a wheel bearing issue in the front passenger side wheel. Even though it did not wiggle or move, it definitely caused the vibrations. While trouble shooting this issue, I also noticed the idiot who worked on the car before me did NOT put the dust cover back on to cover the bearing. It sure didn't take long for the brake dust and everything else to ruin the bearing.....I have to admit.....I was really pissed that a garage would give a wrench to a monkey and turn him loose on a car like this. If I had the name of the garage I would post it here...but unfortunately the work was done before I bought the car.

As long as you have the right tools....it's an easy job to do. There is a fantastic youtube video from 'bimmers garage' that goes through the whole process. I've changed bearings like this before but the guy in this video does a really great job...and does it perfectly. Here is the part 1 of 2 link....part 2 is there too, you just need to do a quick search and it will come right up. The most important thing he does is a before and after what it sounds like. This is key to checking if they're bad.