noise seems to come from rear at 40 mph and up

[enf1945]

I have 1998 328is 92k miles. automatic

at about 40 mph and up i start hearing a humming , droning sound seems to come from the rear of the car.
its not a grindng sound. Car doesnt shake.

if i shift gears in the tramsmission the sound doesnt change.
i dont think its transmission.
definitely not engine.

Is it the muffler ?
the muffler valve does open at 2500 rpm when parked and i rev the engine.
otherwise its closed.
it does sound a little gurgly when in park.not much.
old muffler is stock ,

thanks

[jasonk02]

not sure but sounds like maybe a bad wheel bearing or bushings?

[cabezzzdb8]

Wheel bearings

[JDStrickland]

+1 on the wheel bearings. There are other things that can make noise under the same conditions, but wheel bearings are by far #1 on the list.

[enf1945]

makes more sense .Ill place a new post on this

thanks