At the corner of Calzada de la Luz and Calzada de la Aurora in San Miguel, this hole-in-the-wall tire emporium displays its latest inventory, most of them with laboriously hand-carved treads on previously bald blowouts and finished off with a nice shiny coat of ArmorAll. Like many things in Mexico, little finds its way to the dump unless every last possibility of useful employment has been squeezed out of it.