 A Production TT for roadster-based motorcycles having classes for maximum engine capacities of 250 cc, 500 cc and 750 cc was introduced from 1967 until 1976 when the class was discontinued.The Production TT was reintroduced for the 1984 races in three classes, reduced to two classes on safety grounds for the 1990 races.For the 2005 races the Superstock class replaced the previous 1000 cc & 600 cc Production TT classes that had been part of the race schedule since 1989.