Harley-Davidson FLHTK Ultra Limited Tail Light Bulb Size

Harley-Davidson FLHTK Ultra Limited tail light requires a 3157 bulb size for replacement applications. The chart covers vehicle production spanning 2010 to 2020 with corresponding bulb 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
2010-2020	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 FLHTK Ultra Limited uses the 3157 bulb for the tail light position across all listed model years from 2010 to 2020.
The 3157 is a dual-filament bulb, meaning it contains two separate filaments within a single housing. The higher-wattage filament (27W) serves the brake or turn signal function, while the lower-wattage filament (7W) serves the running light function.
The 3157 follows the T25 wedge form factor, which refers to the tapered, wedge-shaped base used to secure the bulb in its socket without a separate locking mechanism.
The bulb operates at 12 volts, consistent with the standard electrical system voltage found in most production motorcycles.
The 3157 designation is an ANSI standard, meaning its physical and electrical specifications are defined by a recognized industry body and apply uniformly across manufacturers in the United States and Canada.
Because the 3157 is a dual-filament type, single-filament substitutes such as the 3156 are not interchangeable without loss of one lighting function, despite sharing a similar base style.