Almost everyone installing window tint on their vehicle wants to install the darkest legal tint, to maximise the glare and heat reduction benefits, but there are a few issues that can arise if the installation isn’t properly managed, and in this article a professional window tinter shares exactly what needs to be managed, and why.

The first thing you should be aware of is what the darkest legal tint is in your area. This differs in different states and territories around the world. In my home country of Australia, the darkest legal tint permitted on a vehicle is generally one with a VLT (visible light transmission) level of 35%, on all vehicle windows (excluding the front windscreen, which is not allowed to have any window tint except for a visor strip across the top). The only exceptions to this are in the NT and WA. In the NT you are permitted a minimum VLT of 15% for windows behind the driver; and in WA you are allowed 20% VLT on windows behind the driver.

Knowing the regulations is obvious, what isnt though is the technical issues that can come up when installing window film. Most vehicles already have a slight tint in the glass in their front windows, and some have a slight tint on other windows and it’s vital that this is considered when adding tint to a vehicle. Here’s why.

If the factory installed windows on your car already block 30% of light, when a film with the “darkest legal tint” of 35% is added to this glass, it will emit only 35% of light into a window that is already only emitting 70% of light, so the end VLT will be calculated by the addition of both tint ratings, and if you aren’t aware of how this affects your VLT rating, you could unwittingly make your windows illegal.

There are a number of implications here; the first is the risk of being fined. Second and more seriously is the liability risks incurred when your window tint is illegal. If your vehicle is involved in an accident and its illegally dark windows are considered by a court to be a contributing factor to an accident, this could result in the nulling of your insurance policy, leaving you exposed to the full financial culpability of the accident. Additionally criminal charges could apply if property is damaged or people are hurt.

Finally, by modifying a vehicle with illegally dark windows, the vehicle becomes un-roadworthy, which if detected by police means you can’t drive the car again until you get a roadworthy certificate. This means the entire roadworthiness of the vehicle needs to be reassessed, and during this process the illegal tint will have to be removed.

All of these potential issues can be avoided if the proper care is taken to ensure the combined VLT of the installed film, and any existing tint, is calculated prior to the window tint installation. That’s why the combined VLT of both the glass and film really should be considered when you’re selecting the appropriate tint for your car.

Summing up the risks, the critical takeaway from this article is that when it comes to tinting windows, make sure you use a quality film and that your installer has the expertise to be able to offer you the right VLT rating for your situation.