Budd–Michelin rubber-tired rail cars remained obscure in comparison with other competitors for the title, such as the "Pioneer Zephyr" and Union Pacific's M-10000. Rubber-tired rail cars achieved greater success in France, and similar rubber-tired subway cars have been adopted in Canada and Mexico as well as on numerous systems in Europe. During the 1920s, the American Budd Company, at the time a relatively obscure auto-frame supplier, developed an extensive working relationship with the French firm Michelin, which was best known for its tires. In 1929, Michelin built its first rail car, and by 1932 nine of its cars were in operating service, all of
Crumb rubber of small black crumb pieces that came from old tires. The tire crumbs were poured in between the fake grass blades, giving the artificial fields more cushion and support. This was a better solution, as it satisfied athletes and aided in the prevention of major injuries. Rubberized asphalt is the largest market for crumb rubber in the United States, consuming an estimated , or approximately 12 million tires annually. Crumb rubber is also used as ground cover under playground equipment, and as a surface material for running tracks and athletic fields. The following are common classifications of crumb rubber: Retreaders