As glass technicians, what are our responsibilities when replacing tinted glass? Does aftermarket tinting of automotive glass violate the National Traffic and Motor Vehicle Safety Act of 1966 (NTMVS)? Being a student and fan of research, I decided to investigate this issue.

The Federal Motor Vehicle Safety Standard 205, through adoption of ANSI Z26.1 standard for automotive safety glass, dictates automotive safety glass must have 70 percent light transmittance (LT) in the front and side windows. That seems straightforward. However, can the side windows be tinted darker than that directive?

First the facts.

Federal Motor Vehicle Safety Standard

S5.1 – “Glazing materials for use in motor vehicles must conform to ANSI/SAE Z26.1-1996…”

ANSI Z26.1

5.2.3 – “…Safety glazing materials or multiple glazed units intended for use at levels requisite for driving visibility in the motor vehicle shall show regular (parallel) luminous transmittance of not less than 70% of the light, at normal incidence, …”

National Traffic and Motor Vehicle Safety Act of 1966

30122, (b) “A manufacturer, distributor, dealer, or motor vehicle repair business may not knowingly make inoperative any part of a device or element of design installed on or in a motor vehicle or motor vehicle equipment in compliance with an applicable motor vehicle safety standard prescribed under this chapter unless the manufacturer, distributor, dealer, or repair business reasonably believes the vehicle or equipment will not be used (except for testing or a similar purpose during maintenance or repair) when the device or element is inoperative.”

We all have seen side glass tinted beyond the 70 percent LT in the federal standard. Does that mean the aftermarket tinting of glass violates the law? There is a loophole.

The government allows vehicle owners to customize their vehicle in the way they see fit and gives regulation of the customization to the states. For example, a person can paint their car a different color, add a sun visor to the top of a truck, or tint its glass. However, the Federal government will not allow the “repair” business to customize a safety device manufactured into the vehicle.

The Federal government has a definition of a repair facility.

30122, (a) “In this section, ‘‘motor vehicle repair business’’ means a person holding itself out to the public to repair for compensation a motor vehicle or motor vehicle equipment.”

The key words here are “repair business.” An aftermarket tinting company offers a product for customization not for “repair”. They don’t repair the glass by tinting it, they add tinting film as an add-on customization.

Therefore, adding tint to glass is allowed by the absence of federal regulations against it. The only limitation on the “customizers,” or tinting professionals, is the percentage of light transmittance allowed by the state, which is regulated when the vehicle is sold. To make things more challenging, each state’s regulations are different.

What does this have to do with the glass replacement company? An auto glass replacement company is a repair facility according to the federal definition of the word. However, aftermarket tinting added to the glass after it’s replaced, is a customization that must follow state laws which regulate aftermarket tinting. If a replacement company tints the glass either as an added service after the replacement or subcontracts a tinting company to add tinting after the replacement, the replacement company must require all state laws be followed. If not, the repair facility (replacement company) that contracted the work could be held liable.

I am not an attorney. These observations are based on the study of regulations available to the public. However, I reached out to the National Highway and Traffic Safety Administration to see if it could answer this question definitively and I will let you know what they say. In the meantime, make sure you know your state’s laws concerning acceptable tinting guidelines.