Why Are People Putting Blue Dots On Motorcycle Taillights?

If you've been on the road recently, you may have noticed some motorcycles with taillights glowing with a hint of blue besides the usual red, and it's hard not to wonder what the deal with those is. The blue dot phenomenon actually dates back to the 1950s, when it first appeared on hot rods and custom cars as a way to stand out. Now, decades later, they're making a return on some custom choppers, cafe racers, and especially older Harleys.

Part of why they are attractive is how simple the process of adding one is. A biker simply has to insert a tiny, inexpensive blue lens into the taillight. That's usually enough to shift a part of its glow to a purplish tone when illuminated. Some even argue that this second color, when combined with the primary red, enhances visibility. All of this might just lead you to wonder if you should try them too.

The answer is style and nostalgia, specifically throwbacks to post-war America and the golden era of hot rods. Companies like Mooneyes sell blue dot lenses to this day, and many DIY installation guides are available on forums and YouTube. The process is usually as simple as drilling a tiny hole into the taillight lens and inserting the blue lens in it.

Functionally speaking, one theory suggests the blue contrast makes brake lights more visible in fog or low light. That idea has bounced around for decades and may even sound logical at first — after all, emergency vehicles use red and blue lights for a reason. But red light is considered more effective for cutting through fog and grabbing attention on the road due to its longer wavelengths than blue. Meanwhile, the cooler hues created by blue dots may actually reduce visibility, especially on older bikes without LED upgrades. Many riders still argue it's a small trade-off for a classic look, pointing out that they're like tattoos for bikes: a personal statement, even if they don't make practical sense.

They may look cool, but federal regulations are clear about tail lights being red, so you're technically risking a fine. The blue and red combination is generally reserved for emergency vehicles.

However, enforcement is all over the place. Some owners claim they have used blue dots for years without a single traffic stop. Whether you get flagged often depends on where you ride and how lenient your local cops are — many officers focus more on speeding and aggressive driving than on cosmetic mods.

That said, there are a few "loopholes." Washington and Florida, for example, make exceptions for vintage or street rod vehicles. If your motorcycle is registered as a custom or classic, you might skate by. However, it's important to note that these vehicles are generally restricted to specific uses like exhibitions, parades, and club activities, and are not intended for daily transportation.​