Brakes - Hyundai - Santafe :: 2009 - Squealing Rear End

I commute 35mi everyday. It's some stop and go, but at times it's a winding raceway up the valley. Yesterday about 45mins/25 miles into the drive I notice a squeak that's in rhythm with the speed of my car. Braking would dampen the noise, but it would return. I drove it over to the dealership where I work. They say they're booked, but they might have time to look at it in the afternoon between some other appointments. They call me about 2:30pm and say they drove the car around at 30mph, 40mph, and 50mph. No squeak. They say they'll take off the tires to look around. They call me again in 30minutes to say the car is ready, they didn't find anything. My drive home was quiet. Btw it was damp, but not raining yesterday morning. The afternoon was in the 80s and sunny.

This morning it was very damp and misting on the way to work. As I slowed for a toll booth the squeal reappeared and lasted for a few minutes as I got back up to speed. Then it disappeared. I had an idea it was a bad wheel bearing. I remembered reading that driving the car in circles clockwise and counter clockwise could identify a bad wheel bearing. I found an empty lot near the dealership and proceeded to drive in circles 25mph, but fairly tight. Not a peep out of the wheels except for the occasional squeal of the tires. Disappointed with my test, I drove right past the dealer quiet as a mouse.

Finally as I pulled into my work parking lot the squeal reappeared. I found an empty section of the lot and retested my circle hypothesis. Going in circles actually quieted the squeal in both directions. As the car returned to a straight course the squeal reappeared.

2009 Hyundai Santa Fe AWD....