Hello all, this is my first post on this forum! I just finished some work on my car (1995 Cadillac Fleetwood) and I figured I should investigate a whirring noise on my wife's 2013 C Max Hybrid. When I was working on my rotors and repacking the bearings on my Cadillac it got me interested to research the strange noise I have heard coming from my wife's back passenger tire. I read over another thread in this forum discussing tires and alignment as a possible cause of the problem. The noise has been going on for a fairly long time, and it seems to get louder as speed increases. New tires were just installed and I believe a small balance and adjustment was done when they were installed. My concern is that the bearing may be going bad, and I don't want it to lock up on us and cause damage to the car or my wife! From my research, it looks like the car has a different type of bearing than my Cadillac (2 small bearings that you can pack by hand); It looks like a whole assembled unit that you have to take in and out while disconnect an ABS sensor (at least on the Ford Escape/Focus videos I watched). The part from Autozone that I checked out looked like ~$200 apiece!!! :spend: I am sorry for my rambling, just trying to get all the details and things I have done/watched so far. TLDR: Basic whirring noise in the back right tire region, seems to get louder with speed and lessen intensity when the gas is released regardless of speed. We are going on a ~700 trip this coming weekend and I don't want to get stranded if something blows out on the car, so we may have to take the Caddy! Please help! Thank you so much.