Triumph Rocket III Touring Brake Bulb Size

The Triumph Rocket III Touring brake bulb uses a P21/5W size bulb for replacement applications across the specified model line. The replacement chart covers vehicle production years from 2012 to 2017 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.

Bulb Size by Year Range

Years	Bulb Size
2016-2017	P21/5W
2012-2014	P21/5W

Bulb Specifications

Description	Bulb Size
ECE standard (Europe & worldwide). Dual-filament signalling bulb with BAY15d bayonet base. 12V, 21W/5W.	P21/5W

Other Locations

Additional Notes

The P21/5W is the brake bulb type specified for the Triumph Rocket III Touring across the 2012-2017 model years covered in these specifications.
The P21/5W is a dual-filament bulb, with the 21W filament serving the brake/stop function and the 5W filament serving a secondary running light function within the same housing.
The bulb operates on a 12V electrical system, consistent with standard automotive and motorcycle electrical architecture.
The P21/5W uses a BAY15d bayonet base, which is an offset twin-contact fitting. The asymmetric pin placement of the BAY15d base prevents incorrect insertion, as the two pins sit at different heights on the base collar.
The P21/5W is rated under ECE (Economic Commission for Europe) standards, meaning it conforms to internationally recognized regulations for signalling bulbs used in road vehicles.
Because the BAY15d base is specific to dual-filament applications, it is not interchangeable with the BA15s single-contact bayonet base, which is a physically similar but functionally distinct fitting used in single-filament bulbs.