The short answer
Arizona law permits material on the front side windows when the glazing-and-material combination has 33 percent light transmission, plus or minus 3 percentage points. In practical terms, the measured combination must fall within the statutory tolerance; the film's package label by itself does not establish compliance. Those front windows are also limited to 35 percent luminous reflectance, plus or minus 3 percentage points.
Visible-light transmission, often abbreviated VLT, is the share of visible light that passes through both the factory glass and any added film. Because factory glass may already reduce transmission, applying film labeled 33 percent can produce a darker combined result. Ask the installer to select film for the actual glass and, when appropriate, check the completed window with a suitable meter. The law can change, measurement equipment has tolerances, and another state may apply different limits. This answer addresses Arizona passenger-vehicle rules and is general information, not a guarantee that a particular film or vehicle will pass an enforcement inspection.
