Harley-Davidson FLHR Road King Turn Signal Bulb Size

Additional Notes

• The rear turn signal position on the Harley-Davidson FLHR Road King uses two distinct bulb types across the 2007-2020 model range: the 199 and the P21W. Both share identical electrical ratings of 12 volts and 21 watts, and both are single-filament bulbs mounted on a BA15s bayonet base.
• The 199 bulb follows the ANSI standard used in the United States and Canada, while the P21W follows the ECE standard applied in Europe and other international markets. Despite originating from different standardization systems, the two types are electrically and mechanically equivalent in this application.
• The 199 is classified as a variant of the 1156 bulb family. This places it within a widely distributed group of single-filament BA15s signal bulbs, which means replacement stock is broadly available across North American automotive and powersports supply channels.
• The BA15s bayonet base shared by both bulb types features a single contact pin offset to one side, which allows the bulb to be inserted in only one rotational orientation. This design is standard for single-filament signal applications and distinguishes it from the dual-pin BA15d base used in dual-filament bulbs.
• The rear turn signal specification for the FLHR Road King alternates between the 199 and P21W across different model years rather than following a single consistent type throughout the full range. For example, the 2019-2020 models use the 199, while the 2017-2018 models use the P21W.
• Because the 199 and P21W share the same BA15s base and the same 12V/21W rating, physical fitment is compatible across both types. However, substituting one for the other may affect regulatory compliance depending on the market in which the motorcycle is registered or operated.