Idaho Window Tint: 35% Front, 20% Rear, Plus a 3% Tolerance

The permitted darkness depends on where the glass sits. Under § 49-944(1)(b) the front side vents, the front side windows immediately right and left of the driver, and the rear window may carry nonreflective tinting film or a sunscreening device with a light transmission of not less than 35%, subject to a tolerance limit of plus or minus 3%. Under § 49-944(1)(c) the side windows to the rear of the driver may go down to 20%, again with a plus or minus 3% tolerance. Both paragraphs also cap luminous reflectance at no more than 35% with the same 3% tolerance, so mirrored or metallic film fails on reflectance even when it passes on darkness. The statute defines both terms itself in paragraphs (1)(e) and (1)(f) as ratios of total light passing through, or reflected outward by, the material, so an Idaho officer and an Idaho installer are working from the same definitions.

The tolerance limits are the newest part of the section. They were added by 2023 Session Laws ch. 112, sec. 1, the only amendment to § 49-944 since 2000. Their practical effect is that a meter reading of 32% on a front side window is inside the statutory band, and a reading of 17% behind the driver is too. Nothing in the section tells an officer to apply the tolerance only to calibration error, so the band is part of the standard itself.

The windshield is handled separately in § 49-944(1)(a). Nonreflective film may not be applied below the AS-1 line, and where no AS-1 line is identifiable the film may not go below a line extending six inches below and parallel to the exposed windshield. That is a placement rule, not a percentage rule: above the line there is no transmission figure at all for an ordinary vehicle.

Idaho grants a medical exception in § 49-944(4) rather than a medical exemption from the rules. It substitutes its own numbers: not less than 70% plus or minus 3% on the front windshield and not less than 20% plus or minus 3% on the windows, with reflectance still capped at 35% plus or minus 3%. It requires written verification from a licensed physician that the driver or a passenger must be protected from exposure to sunlight or heat for medical reasons associated with past or current treatment, and that verification must be carried in the vehicle. There is no permit, no sticker and no state registry behind it.

Factory glazing is protected outright. Section 49-944(5) says nothing in the section makes it illegal to operate or sell a vehicle whose windshield or windows were composed of, covered by or treated with material the vehicle was sold with when new, or could have been equipped with when new as standard or optional equipment under federal law at the time of manufacture. Privacy glass moulded into a pickup or SUV at the factory therefore never has to meet the 20% or 35% figures.

Section 49-944(3) authorises the Idaho State Police to promulgate rules implementing the section. It has not used that authority for tint. The State Police motor vehicle rules at IDAPA 11.07.01 do nothing but incorporate the SAE Ground Vehicle Lighting Standards Manual, the Idaho Department of Education school bus manual, and parts 392, 393 and 571 of 49 C.F.R.; the words transmittance, transmission, tinting and sunscreening appear nowhere in IDAPA 11.07 at all. So the meter reading has no administrative gloss, and the statute is the whole standard.

Section 49-944(6) makes any violation an infraction. 50. Section 49-944(2) reaches the seller as well as the driver: no person may operate on the public highways, sell, or offer to sell a vehicle whose windshield or windows do not comply, so a dealer or tint shop is exposed on the same terms as an owner. Idaho has no periodic motor vehicle safety inspection, so nothing routinely puts a meter on your glass. The vehicle emission inspection and readjustment programmes referenced in Idaho Code § 49-202(12)(f) are run by a city or county under its own ordinance as part of an approved state implementation plan, they test tailpipes rather than windows, and their only registration consequence runs through the transportation department after notice and a hearing.

Separately, § 49-202(12)(a) lets the department revoke the registration of a vehicle it determines is unsafe or unfit to be operated or is not equipped as required by law.