A tinted film is applied to selected windows to darken or shift the color. Professional installation is recommended as do-it yourself may have poor results. Most states have various laws on tinting. For example, California’s requirements are:
- The windshield and front driver’s side and passenger’s side windows cannot receive any aftermarket tinting.
- If the rear window of a vehicle is tinted, the vehicle must have outside rearview mirrors on both sides.
Keep in mind that tinting may make it more difficult to see at night and while in the sun, it may increase the air-conditioning load in the summer (but reduce the heating load in the Winter). Film applied to the long slope of the rear window may also add distortion.