Harley-Davidson FLHRC Road King Classic Tail Light Bulb Size

Harley-Davidson FLHRC Road King Classic tail light uses a 3157 bulb size. The replacement chart covers 2007 to 2013 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.

Bulb Size by Year Range

Years	Bulb Size
2007-2013	3157

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Dual-filament wedge bulb (T25). 12V, 27W/7W.	3157

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Additional Notes

The Harley-Davidson FLHRC Road King Classic uses the 3157 bulb for the tail light position across the 2007-2013 model years.
The 3157 is an ANSI-standardized bulb type recognized across the United States and Canada, meaning it conforms to a defined set of electrical and physical specifications shared by all compliant manufacturers.
It is a dual-filament bulb, which allows a single unit to serve two distinct lighting functions, typically a lower-intensity running light and a higher-intensity brake light, within one housing.
The bulb operates on a 12-volt electrical system and draws 27 watts on the high filament and 7 watts on the low filament, reflecting the difference in brightness between the two operating modes.
The 3157 follows the T25 wedge form factor, a designation that describes the physical shape and base type of the bulb used to seat it within the socket.
Because the 3157 is a dual-filament type, substituting it with a single-filament equivalent such as the 3156 would result in the loss of one lighting function and is not a compatible replacement for this application.