Harley-Davidson FLHTK Ultra Limited Brake Bulb Size

Harley-Davidson FLHTK Ultra Limited uses a 3157 bulb size for brake applications. The replacement chart covers 2010 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
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 across all listed brake light fitments from 2010-2023.
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 is a dual-filament type, operating at 27 watts on the high-intensity filament and 7 watts on the low-intensity filament, which allows it to serve both brake and running light functions within a single unit.
The 3157 is classified as a T25 wedge bulb, where T25 refers to the tubular glass envelope with a 25mm width, and the wedge base describes the plastic base design that holds the bulb in place without a separate metal socket.
Operating voltage is rated at 12 volts, consistent with standard 12V automotive and motorcycle electrical systems.
The dual-filament construction of the 3157 means a single-filament replacement such as the 3156 would not replicate full brake and running light functionality, making filament count a critical factor in substitution decisions.