Window tint laws: federal rules vs. state limits

The federal layer

Federal Motor Vehicle Safety Standard No. 205 governs glazing in new vehicles and vehicle equipment. NHTSA explains that glazing in areas requisite for driving visibility generally must provide at least 70 percent light transmittance. The rule also addresses the windshield shade-band area and the AS-1 marking.

Federal law also restricts manufacturers, dealers, distributors, and repair businesses from making compliant safety equipment inoperative. NHTSA has repeatedly explained how that restriction applies when a commercial business installs film on a used vehicle.

The state layer

State window tint laws regulate vehicle registration and operation after the first retail sale, including owner-installed tint, inspection, reflectivity, side and rear windows, windshield bands, medical exceptions, certificates, and enforcement. Those requirements vary and can change.

That is why an online chart should be treated as a starting point, not the final answer. Confirm the current statute or motor-vehicle agency guidance for the registration state and make sure the installer measures the combined glass-and-film transmittance rather than relying only on the film's advertised number.

Before you buy or install film

Use this order of operations to avoid paying twice or failing inspection.

• Identify the vehicle class, registration state, and each window being tinted.
• Read the current state rule for visible-light transmission, reflectivity, colors, windshield limits, stickers, and medical exemptions.
• Measure the factory glass because existing tint changes the final combined result.
• Ask the installer to document the product and measured final transmittance.
• Re-check the destination state's rules before moving or registering the car elsewhere.