i think he's referring to a more groaning-like noise, from when u lightly apply and release the pedal, for instance u are facing down a hill and slightly let your foot off the pedal and u slowly begin to creep down the hill all the while your brakes are groaning really loud inside the truck, i've always wondered about that too, it never really worried me though, since i changed my brakes these crappy pads do it all the time <img src="/forums/images/graemlins/angry.gif" alt="" />