The Triumph Bonneville T100 uses a 9003 bulb size for both high beam and low beam headlight applications. The replacement chart covers vehicle production years spanning 2002 to 2018 with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Triumph Bonneville T100 uses the 9003 bulb size for both high beam and low beam headlight functions across the 2002-2018 model years covered in the specifications.
The 9003 is a dual-filament halogen bulb, meaning a single bulb unit contains two separate filaments to serve both high and low beam functions within one housing.
The 9003 operates on a 12-volt electrical system and carries a wattage rating of 60W on the high beam filament and 55W on the low beam filament.
The 9003 uses a P43t base, which is a bayonet-style mount with a 43mm collar, and this base type determines physical fitment into the headlight housing.
The 9003 designation follows the ANSI standard used in the United States and Canada. It is functionally equivalent to the European H4 bulb type, though the two share the same electrical and physical characteristics under different regional naming conventions.
Because the same 9003 bulb serves both beam functions on the Triumph Bonneville T100, a single bulb replacement addresses both high and low beam output simultaneously.