Very true. Most all pistoins are plated with tin. It's purpose is to keep the piston from growing cooties in the box. One piston that I use many of, that is not tin plated, is Mahle. The tin plating is a couple of tenths thick. To depend on two tenths worth of tin plating, to keep you safe, is not my idea of good engineering. If I measure a used piston at two-three thousanths under, where do you suppose the tin plating went to? Plateau honing is the key, not tin plating.