My truck just developed an unusual noise at speeds above 70 MPH. I know trying to describe a noise is difficult - but here goes. It is not a metallic noise like something rattling or hitting - but more of a growl - a loud sound that pulsates - kinda like a tire noise. My tires seem OK, but I was wondering if something else could be making the noise. Does a VP44 make any loud noises when it starts to go out?