loud squeel

i have a very loud squeel coming from the front end of my car. Ifigured it had to be the wheels. The fan runs for a while after the car is turned off and sounds fine. I will try to explain it the best i can. After driving for like 15 minutes or more everyonce in a while (not all the time) i hear the sound. If i jerk the wheel it will sometimes quite and sometimes quit for a sec and then start again. When the car is in neutral it still happenes, and if it starts making the noise and i turn the car off and let it roll it still does it. when the car has come to a stop the noise is gone. Sometimes the noise is farly soft but eventually get really loud. any ideas?