Are blue headlights illegal in Pennsylvania?

Answer 1

Blue lights are allowed only on authorized (police, fire, ambulance, snow removal) vehicles. Headlamps on all vehicles are required to emit _white_ light. The allowable range of "white" is rather large. It can contain a fairly substantial tint towards any color (including blue) and still be considered legally white. That's why even the reputable brands contain bulbs with blue glass that advertise "whiter" light. It's a misnomer; tinting the light towards blue, even if it stays within the allowable white range, does not make the light "whiter". And even if you buy legal "whiter" bulbs, if your headlamps look like they might not be legal, you can expect extra attention from the cops, whether they scrutinize your headlamps or simply notice your car doing 64 in a 55 instead of the car next to you with normal headlamps doing 67 in a 55. Moreover, any bulb that has colored glass is filtering out a significant amount of the light that would be reaching the road if the bulbs had proper colorless clear glass. It's a bad tradeoff: extra hassle from the cops in exchange for poorer nighttime and bad-weather seeing. Moreover, be aware that different headlamp technologies look different because they create light differently. HID ("Xenon") and the newest LED headlamps produce a colder white light than traditional halogen headlamps, but they're all white. It is illegal (and dangerous) to try to "convert" halogen headlamps into Xenons with an "HID kit".

Every light and reflector function on the outside of a vehicle has a required color. Front side marker lights and reflectors have to be amber, rear ones have to be red. Tail lights and brake lights all have to be red. Front turn signals have to be amber. Backup lights have to be white. In a couple of cases there are two different colors allowed (front parking lights can be white or amber, rear turn signals can be amber or red) as long as they're not mismatched on the same car. Putting nonstandard colored lights on the car is like hanging a sign on it that says "Stop me, officer! There are probably more things you can write me a ticket for, not just these illegal lights!".