^ Part of the point of a narrow tire is the ability to run higher pressure. Fatter tires spread the rubber out on the assumption that a lower pressure will be used and the contact patch is wider. If you run them at as high a pressure as a narrow tire, they won't last as long, as most of the rubber is not used. They will wear fast on a narrow portion in the center. The narrow tire (given the same mass of rubber) will have thicker rubber in the middle (contact patch). Given that, the graph above has minimal practical value in selecting tire size.