Harley-Davidson FLHRS Road King Custom Headlight Bulb Size
The Harley-Davidson FLHRS Road King Custom uses a 9003 bulb size for both high beam and low beam headlight applications. The replacement chart covers 2004 through 2007 model years 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 9003 bulb is the sole bulb type specified across all headlight positions on the Harley-Davidson FLHRS Road King Custom, covering model years 2004-2007.
The 9003 is a dual-filament halogen bulb, meaning a single bulb unit contains two separate filaments, one rated at 60 watts for high beam operation and one rated at 55 watts for low beam operation.
Because both the high beam and low beam headlight positions on this motorcycle share the same 9003 specification, a single bulb type serves both functions within the headlight assembly.
The 9003 operates on a 12-volt electrical system, which is standard for automotive and powersports applications of this type.
The 9003 uses a P43t base, which is a bayonet-style mount with a 43mm flange. This base type is a physical fitment standard, and bulbs with a different base are not mechanically compatible with this socket.
The 9003 carries ANSI standardization applicable in the United States and Canada. It is functionally equivalent to the international HB2 designation, though the two designations originate from different standards bodies.
The 9003 and H4 bulbs share the same P43t base and dual-filament configuration, and the two are widely regarded as interchangeable in practice, though the 9003 designation reflects the North American ANSI standard while H4 reflects the ECE standard used elsewhere.