Ever had to pull over off the road and then pull back on and have a loud squeel come from your wheel. My son was traveling out to live with me and had pulled over to change drivers. When he pulled back on the road he heard a loud squeeling coming from his wheel. After pulling back off and jacking up his wheel he found that a small rock had gotten caught between his brake roter and the backing plate. During the years that I have been a mechanic I have run into this problem many times. The reason I am writing about it is that the sound is similar to a brake pad sgueel when your brakes are worn out. I would sugest that when you have your brakes checked, especially if they are squeeling that you get the mechanic to let you visually see the brake pads when he has the tire off. Could save you a few dollars.