Devices or Equipment Obstructing or Reducing Driver's View
No motor vehicle may be driven when the driver's view out of the windshield and side or rear windows is obstructed. Objects fixed to the vehicle or the vehicle's windows, including snow and ice, can obstruct the driver's view.
It is illegal to block your view of the environment by doing any of the following:
Placing signs, stickers, or objects on the windshield.
Hanging items from the rear-view mirror.
Blocking your view with similar items on the side or rear windows.
Signs on windows have contributed to crashes in the past because the driver didn’t see a child, a bicyclist, or even a truck coming at him or her from the side.
Tinted safety glass is only allowed if the glass meets US DOT standards and you have it placed in permitted portions of the windows. The permitted areas include:
The rear side windows
The rear window, as long as an outside mirror is attached to the front passenger door
The sun or moon roof
The tint may not be red, amber, or reflective.
A clear, colorless, and transparent film may be applied to the front side windows to reduce ultraviolet rays, as long as the driver has in his or her possession a certificate from the installer certifying that the material meets the requirements of the vehicle code and the film does not bubble up or become torn, thus reducing your visibility.
Sun screening devices on the front side windows may only be used when the driver (or passenger seated in the front seat) has a written document from his or her physician and surgeon or optometrist, stating that shading from the sun is necessary by reason of a medical or visual condition. Any such sun screening devices must be green, gray, or a neutral smoke color and have a luminous transmittance of not less than 35%, and must be removable and may not be used during darkness.
You are not allowed to wear glasses that have such wide temples that you cannot see to the sides.