Window tint is applied to vehicles for several reasons. It is often installed to keep the inside of the vehicle cooler, and some people install it because they believe it makes the car more attractive. Window tint can also prevent glares from the sun, and prevent harmful UV rays from reaching the car’s occupants. Some people actually have a valid medical need to keep their windows tinted. Regardless of the reason for window tint on a vehicle, car owners must abide by the window tinting laws. The lower the percentage, the darker the film. ... The VLT is the percentage of visible light the tint allows to pass from the exterior of the window to the interior of the vehicle, which means that a 5% VLT means that only 5% of exterior light is allowed to pass through the glaze, which is why it's so dark.