Originally Posted by
BarracksSi
I can be completely unable to hear a car to my rear if the one next to me is loud enough.
Well of course louder vehicles drown out quieter ones. This happens every day no matter what type of vehicle the quieter one is. Often it is a motorcycle drowning out regular cars.
And yes, to S.H. at lower speeds tire noise is less, but at lower speeds you are going to see the vehicle long before you hear it.
Al