A trucker in Amarillo teaching you the door trick is a pretty specific story and I want to know what the trick actually is. Does it mean you park next to a building and use the door as a reference line to set your side mirrors so you see a sliver of your own car and the lane beside you? Because I tried that once and still got a blind spot the size of a small dog. How far out did you have it set before he fixed it, and did you notice a real change on the road after?