GEMPRO BLOG · COMPLIANCE

DOT & STREET-LEGAL
BASICS FOR
AFTERMARKET LIGHTING.

Aftermarket lighting rules in the U.S. combine a federal baseline (FMVSS 108) with state-level rules that vary on color, placement and how lights may be used on public roads. This guide covers the general principles — always confirm the specifics for your state before buying.

Color generally matters more than brand

Across most states, forward-facing lights are expected to be white or amber, and rear-facing lights red or amber. Blue and red forward-facing lights are broadly restricted because they're associated with emergency vehicles, regardless of the product's marketing.

Placement and aiming

Replacement bulbs and housings are expected to sit in the same functional position as the factory light and aim so they don't blind oncoming drivers. This is also why beam pattern (covered in our LED buying guide) matters for legality, not just visibility.

Auxiliary lights: on-road vs off-road use

Many auxiliary light bars and pods are sold for off-road use only. Some states allow them on public roads if covered or wired to a separate switch that's off during normal driving; others restrict them regardless. Check your state's vehicle code before wiring an auxiliary light to run with your headlights.

What this means when you buy

• Match replacement bulb color to the light position's factory color.
• Confirm beam alignment stays correct for any bulb or housing you're considering.
• Treat off-road-labeled lighting as off-road only unless your state explicitly permits road use.
• When in doubt, check your state DMV or vehicle code — regulations are not uniform nationwide.

This article is general information, not legal advice. Confirm current requirements with your state's motor vehicle authority before purchasing aftermarket lighting.

Related reading: see How to Choose the Right LED Headlight Bulb for fitment basics, or LED vs Halogen: What Actually Changes if you're still deciding whether to upgrade.