The one-sentence version
Minnesota holds side and rear windows to roughly 50 percent light transmittance across the board. Wisconsin allows noticeably darker film behind the driver. Your vehicle is generally held to the law of the state it is registered in, and you can be stopped in the state you are driving through.
Wisconsin
Wisconsin's vehicle window requirements sit in the state statutes on windows and windshields and the Department of Transportation's administrative rules. In broad terms, for a passenger car:
| Window | Wisconsin (passenger car) |
|---|---|
| Windshield | Non-reflective film permitted above the manufacturer's AS-1 line |
| Front side windows | Must allow roughly 50% of light through or more |
| Rear side windows | Roughly 35% or more |
| Rear window | Roughly 35% or more |
| Reflectivity | Reflective / mirrored film not permitted |
| Colour | Red, amber and colours resembling signal lighting not permitted |
Multipurpose vehicles — many SUVs and vans — are treated more permissively behind the driver than sedans. Wisconsin also provides for medical exemptions with physician certification, and the documentation needs to be with the vehicle.
Minnesota
Minnesota is more restrictive and simpler. Minnesota Statute 169.71 prohibits side and rear windows with a light transmittance of less than 50 percent, plus or minus three percent, or a luminous reflectance of more than 20 percent, plus or minus three percent.
| Window | Minnesota |
|---|---|
| Windshield | Film that reduces light transmittance not permitted |
| Front side windows | No less than 50% light transmittance (±3%) |
| Rear side windows | No less than 50% light transmittance (±3%) |
| Rear window | No less than 50% light transmittance (±3%) |
| Reflectivity | No more than 20% luminous reflectance (±3%) |
Minnesota's exemptions are worth knowing
The statute carves out several categories, including rear windows of pickup trucks, rear and side windows behind the driver on vans, limousines, funeral vehicles and law enforcement vehicles, factory glazing that complies with Federal Motor Vehicle Safety Standard 205, and documented medical exemptions.
So a Minnesota pickup owner and a Minnesota sedan owner are not in the same position at all — which is a distinction almost nobody knows about until they ask.
The border problem
Here is the scenario we see constantly. A Woodbury or Stillwater driver crosses the river, gets 35 percent film on the rear windows because Wisconsin allows it, and drives home to a state where that film is not permitted on their Minnesota-registered vehicle. It looks great. It is also a problem waiting for a traffic stop.
It runs the other way too. A Wisconsin driver who commutes into the east metro daily is legal at home but is driving through a state with a stricter standard every morning.
What we do about it
- We ask where the vehicle is registered before we talk about film, not after.
- If you drive both sides regularly, we will talk through a specification that keeps you comfortable on both.
- We will not quietly install a film that puts you outside your own state's limit. If you want it anyway after we have explained it, that is your call to make with the facts in hand.
- Heat rejection and light transmittance are different properties. Modern ceramic films reject a great deal of heat at legal light levels — you do not have to choose between comfort and compliance the way you did fifteen years ago.
Two things people get wrong about VLT
First, the number is the total for the window, not the film. Factory glass already blocks some light, so a 50 percent film on a window that is already 80 percent does not give you a 50 percent window. Reputable installers measure the finished result with a meter.
Second, factory privacy glass is not tint film. Many SUVs and trucks come from the factory with dark rear glass that is manufactured that way and treated differently under the rules than applied film.