Window Tint: 24 Percent Light Transmission Limit

The operative numbers sit in RCW 46.37.430(5)(a): net film sunscreening on any window other than the windshield must have "a total reflectance of thirty-five percent or less, and a light transmission of twenty-four percent or more, where the vehicle is equipped with outside rearview mirrors on both the right and left." Both conditions matter. The 24 percent floor is not the rating printed on the film's box, because RCW 46.37.430(2)(b) defines "net film screening" as "the total sunscreening or coloring material applied to the window that includes both the material applied by the manufacturer during the safety glazing and any film sunscreening or coloring material applied after the vehicle is manufactured." A rear window that leaves the factory as dark privacy glass is already close to or below the limit before any film goes on, and a 35 percent film over clear front glass lands well under 24 percent once the glass itself is counted. The same subsection bars stacking: "Installation of more than a single sheet of film sunscreening material to any window is prohibited."

Four film types are illegal at any darkness under RCW 46.37.430(5)(g): mirror finish products; red, gold, yellow or black material; and film in liquid preapplication form that is brushed or sprayed on. Under RCW 46.37.430(5)(f), once film is on any window other than the windshield, the outside mirrors on both sides must be positioned to give the driver a view of the roadway at least two hundred feet to the rear through each mirror.

The windshield is treated separately. RCW 46.37.430(5)(e) permits a greater degree of light reduction "along the top edge of the windshield as long as the product is transparent and does not extend into the AS-1 portion of the windshield or extend more than six inches from the top of the windshield." Two limits ride together there: the strip must be see-through, and it stops at whichever of the AS-1 marking or the six-inch line comes first. The same subsection separately allows "Clear film sunscreening material that reduces or eliminates ultraviolet light" over the whole windshield, which is why a clear ceramic UV film is legal on Washington glass while a smoked one is not.

A wide class of vehicles escapes the 24 percent floor behind the driver. RCW 46.37.430(5)(b) lets hearses, collector vehicles, limousines, passenger buses used to transport persons for compensation, ambulances, rescue squad vehicles, other emergency medical vehicles licensed under RCW 18.73.130, and any vehicle the manufacturer identifies as a truck, motor home or multipurpose passenger vehicle under 49 C.F.R. Sec. 571.3 run darker than 24 percent on any window to the rear of the driver, provided reflectance stays at 35 percent or less and both outside mirrors are fitted. Because most pickups and SUVs are built as trucks or multipurpose passenger vehicles, that carve-out reaches a large share of Washington's fleet, but it never touches the two front side windows or the windshield.

The medical exemption is broader than the vehicle-class one. RCW 46.37.430(5)(d) permits a greater degree of light reduction "on all windows and the top six inches of windshields" of a vehicle driven by or carrying a person who possesses written verification from a licensed physician that they must be protected from sunlight for physical or medical reasons. The statute asks only for that written verification; it does not create a permit issued by the Department of Licensing or a placard issued by the State Patrol.

Washington also polices the shop, not just the car. Under RCW 46.37.430(5)(c), a person or business tinting windows for profit within restricted areas of the glazing system must affix a sticker to the driver's door post next to the manufacturer's identification tag, certifying that the application meets the chapter's light transmission, reflectance and placement standards. The sticker must be no smaller than three-quarters of an inch by one and one-half inches and no larger than two inches by two and one-half inches, must survive harsh weather, and must clearly show the installer's business name and state tax identification number. Police vehicles get their own rule: RCW 46.37.430(9) exempts the side and rear windows of law enforcement vehicles, but when such a vehicle is sold to a private individual the film must be brought into compliance or the buyer must be given documentation saying so before the vehicle is operated.

110(8)(a) unless the court finds the driver indigent. 110(1)(b) the court may waive or remit the base penalty. The installer is exposed to far more. 435(2), as amended in 2019 by 2019 c 438 s 1, makes providing or receiving compensation for such an installation a gross misdemeanor. 010(1) authorizes State Patrol inspection stations only for commercial motor vehicles, school buses and private carrier buses. 060 separately empowers any peace officer to impound a vehicle found defective in equipment so as to be unsafe until it is corrected, with the cost of impound and storage paid by the owner.