Well, I have a wheel bearing going out. A very slight, almost unnoticeable hum started last week, and has steadily grown worse. Got it up on a hoist and wiggled each wheel - passenger rear has a very slight click when pushing & pulling on opposite sides of the wheel. The noise sounds like it's coming from the front though, so I ordered two and will be replacing both passenger hubs when the parts arrive. Later on this spring/summer when I upgrade the brakes I'll replace the drivers side hubs as well. I am up to about 120k miles at this point so it's not surprising.