Tint Darkness

• In California, the darkness of a tint is measured by visible light transmission (VLT) percentage, which is the percentage of visible light allowed in through the combination of film and the window. Under state law, the front driver's- and passenger's-side windows of any vehicle must let in more than 70 percent of light in if they're tinted. However, any shade of tint can be used on back side windows and the rear window of the vehicle.
  
  

Light Reflection

• Some tinting film contains metallic elements that reflecting incoming light and reduce the glare and heat generated by visible light, similar to sunglass lenses. Under California law, the amount of reflection in the front side and back side window tint can't be greater than that of a standard window. There's no limit on the reflective properties of the rear window tint, but only a nonreflective tint is allowed on the top 4 inches of a vehicle's windshield.
  
  

Colors

• The color of tint film is limited in California. Black, brown and shades in between are allowed, but the colors of amber, blue and red are illegal in the state.
  
  

Side Mirrors

• For visibility and safety reasons, a vehicle must have outside rear-view mirrors on both the driver and passenger sides if the vehicle's rear window is tinted.
  
  

Windshields

• California law prohibits any person from driving any motor vehicle that has a tint film on the windshield. The exception is clear, colorless, and transparent material that has the specific purpose of reducing ultraviolet rays. Under the law, if or when this material becomes torn, bubbled or too worn, it has to to be removed or replaced.