not sure how relevent it is, but before ours was hit by the train, I was feeling what I describe as tire noise. I know it wasn't. It was def. readend noise. It never changed pitch for pavement type to pavementtype. The faster I went, the more noticable it became.It did not follow engine RPM only speed of car. I got under the car, and could not duplicate, or hear the noise while hand rotating things. No real back lash between drive shaft and wheels. Dodge said they never heard or found it, figures, car was still under warrenty. Never had a chance to figure it out, the train took care of that.