Harley-Davidson FLHRXS Road King Special Brake Bulb Size

Harley-Davidson FLHRXS Road King Special uses a 3157 bulb size for brake applications. The replacement chart covers 2017 to 2023 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
2022-2023	3157
2017-2020	3157

Bulb Specifications

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

Other Locations

Additional Notes

The Harley-Davidson FLHRXS Road King Special uses the 3157 bulb across all listed model years, spanning 2017-2020 and 2022-2023.
The 3157 is an ANSI-standardized bulb type, meaning its specifications are governed by a formal industry standard recognized in both the United States and Canada.
This bulb follows the T25 wedge form factor, which refers to its tubular shape and the wedge-style base that secures it directly into the socket without a separate bayonet or screw fitting.
The 3157 operates on a 12-volt electrical system, consistent with standard automotive and motorcycle DC power configurations.
Its dual-filament design runs at 27 watts on the high-intensity filament and 7 watts on the low-intensity filament, allowing a single bulb to serve both brake and running light functions within one housing.
Because the 3157 is a dual-filament type, substituting it with a single-filament equivalent would result in the loss of one lighting function, making filament count a critical factor in replacement selection.