Smoked headlights and tailights are a popular fad for customising an automobile's appearance. Typically this entails a film, darkening paint or pre-cut plastic cover being placed over a headlight to change the visual appearance. Despite the popularity of such modifications, it is generally illegal to operate a motor vehicle where the headlights have been modified in such a fashion.
Smoked Headlights Generally
Automobile laws vary from state to state, but the vast majority of jurisdictions prohibit tinting or smoking of headlights, because this reduces the light output and can change the colour of the light. For example, Pennsylvania prohibits under 175.66g the obstruction of a headlight by screens, bars or any device that will obscure, change the colour or obstruct the beam.
In addition to smoked or tinted headlights being illegal for use on-road, headlights modified in such a fashion will not pass a state motor vehicle inspection. A vehicle which fails inspection cannot be registered for on-road use.
Restrictions on smoked or tinted headlights generally apply to on-road operation of a vehicle and thus do not apply to vehicles intended for display or off-road operation.