1.1 This specification covers seven classes of carbon steel tires for railway and rapid transit use.

1.1.1 Class A -For untreated driving tires for locomotives in passenger service.

1.1.2 Class AHT -For heat-treated driving tires for locomotives in passenger service.

1.1.3 Class B -For untreated driving tires for freight locomotives and tires for locomotive-truck, tender-truck, trailer and car wheels, and miscellaneous service.

1.1.4 Class BHT -For heat-treated driving tires for freight locomotives and tires for trailer wheels.

1.1.5 Class C -For untreated tires for switching locomotives.

1.1.6 Class CHT -For heat-treated driving tires and switching locomotives and tires for locomotive-trucks, tender-trucks, trailer and car wheels, and miscellaneous service.

1.1.7 Class DHT -For heat-treated driving tires for locomotives with light braking conditions, heavily loaded trailer tires, and car wheels where off-tread brakes are employed.

1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are provided for information purposes only.