Introduced in 1998, the Buell Pro Thunder Series is an enthusiast class which blends the exhaust note of single-, twin- and three-cylinder engines with modern chassis design and components. Engine displacement limits vary, depending on whether the engine is air- or water-cooled, as well as the type of valve actuation.

The class is restricted to motorcycle engines produced for street use and available in North America through retail dealers and distributors. Single-cylinder engines are exempt from this requirement. Engine modifications are allowed and racing slick tires may be used.

Qualifying procedure:
Heat races are used to determine the starting grid for Buell Pro Thunder final race. The winner of the fastest heat is the pole winner. Riders are then arranged on the final race grid alternately, based on their performance in heat race #1 and #2.

The AMA Pro Thunder final race is 60 kilometers in length.