9.5.3 - All vintage roadrace numbers must be black on a white background, except: Sportsman,
black numbers on “school bus yellow” background, and Novice Historic Production,
red numbers on white background, Sportsman and Novice Historic Production
machines use 10x12-inch rectangular number plates; all others use rectangular plates
9.5.4 All Vintage Superbike numbers must be white numerals on a green background
9.5.5 - BoT, SoS and SoT machines may use any number plate background color; numbers
can either be black or white, whichever provides the best visibility.
9.5.6 - Numbers must be at least seven-inches high, block style, with a stroke width of one inch
and legible. There must be no less than 1/2-inch of space between numbers, and
between the numbers and the outside edge of the number plate. If a rider’s assigned
number will not fit into a 9x11-inch oval, a larger background may be used, up to a
9.5.7 - All machines must display three number plates -- one mounted on the front and one
on each side, mounted in such a manner that it will not be blocked by the rider in the
normal racing (seated) position.