Triumph Rocket III Touring Tail Light Bulb Size

The Triumph Rocket III Touring tail light requires a P21/5W bulb size for proper illumination. The replacement chart covers vehicle production spanning 2012 to 2017.

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	US Type	EU Type	Shop
2016-2017	1157	P21/5W	Check Price
2012-2014	1157	P21/5W	Check Price

Bulb Specifications

Description	Type	Shop
ECE standard (Europe & worldwide). Dual-filament signalling bulb with BAY15d bayonet base. 12V, 21W/5W.	P21/5W	Check Price
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. 12V, 21W/5W.	1157	Check Price

Other Locations

Additional Notes

The P21/5W is the tail light bulb type used across all listed model years of the Triumph Rocket III Touring, spanning 2012-2014 and 2016-2017.
The P21/5W is a dual-filament bulb, meaning it contains two separate filaments within a single glass envelope, allowing it to serve two distinct lighting functions from one unit.
The bulb operates on a 12V electrical system and draws either 21W or 5W depending on which filament is active, with the higher wattage filament typically assigned to the brake or turn signal function and the lower to the running light.
The P21/5W uses a BAY15d bayonet base, which is an offset twin-pin fitting. The asymmetric pin placement of the BAY15d base ensures the bulb can only be inserted in one orientation, preventing incorrect filament assignment.
The P21/5W is governed by ECE (Economic Commission for Europe) standards, making it a globally recognized type used across European and international markets rather than a region-specific part.
Because the BAY15d base is offset, it is not interchangeable with the similarly named BA15d base, which uses symmetrically placed pins. Substituting one for the other is not physically possible without modification.