I bought a set of used wheels that had tires already mounted on them and had been driven for approx. half the tread life. Since there were no designations to which side of the car these origainally came off of I put them on my car and have enjoyed 20,000 trouble free miles. Subsequently I was told that it is dangerous to drive on radials that are turning in the opposite direction from the original direction. Something about "setting" the cord. What about this, myth or fact?