are the stock Michelins directional or non-directional? and how should they be rotated? front to back and vice-versa or diagonally? i've always wondered why it's called a TIRE rotation and not a wheel rotation cuz that's what it is. it's not like you're taking the actual tires off and switching them which would be nice. it just sucks to hafta move the non-scratched wheels from the driver's side over to the passenger side where contact with the curb happens sometimes with me. speaking of scraped rims, how much would it cost, per wheel, for a garage to polish the scratches out?