Harley-Davidson FLHRC Road King Classic Brake Bulb Size

Harley-Davidson FLHRC Road King Classic uses a 3157 bulb size for brake applications. The replacement chart covers 2007 through 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 3157 is the brake bulb size specified for the Harley-Davidson FLHRC Road King Classic across all listed model years, spanning 2007-2013.
The 3157 bulb follows the ANSI standard, which is the recognized specification system used in the United States and Canada for automotive lighting components.
As a dual-filament bulb, the 3157 operates on two separate filaments within a single housing, one rated at 27W for the brake and turn signal function and one at 7W for the running light function.
The bulb operates on a 12-volt electrical system, consistent with standard 12V motorcycle electrical architecture.
The 3157 is classified as a T25 wedge-type bulb, referring to its tubular glass envelope and wedge base, which seats directly into a socket without a separate metal base or bayonet pins.
The T25 designation indicates the glass envelope width expressed in eighths of an inch, placing it in a well-established size category commonly found across a wide range of vehicle lighting applications.
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, making filament count a critical factor in fitment.