I now have 14k miles and I can maybe count the chips on 1 hand... not a single one behind any of the wheels. Opti-coat is a very hard coating. Much of the advice here IMO is not that great and the OP should be very cautious with it. This is NOT at all meant to come across to be a jerk or anything, though I know it will. Like I told the OP though... read that link.