The sound changing when turning definately sounds like a bearing thing.

Just went through this with one of my Sentra's. Sounds like a fast pitched rumble and when I turned and unloaded that wheel the sound would go away but get worse when I turned the other way and loaded the wheel.

If not tread wear probably bearing.

But then there are some other possiblities, ball joint, etc.

Jack the car up and with the wheel off the ground grasp the wheel and give a little shake. If the bearing is junk you'll feel a little play, compare to the other side. You should feel the difference.

Joel