While most car makers offer darkened privacy glass on new vehicles, owners of older vehicles often look to window tinting to cut the UV filtering into their car. We explore the latest Australian laws for window tinting and whether you should bother…

IT’S USUALLY in Spring that you start to see window tinting ads appear on TV, online and in newspapers. While it’s possible to purchase window tinting for your home and your car from auto accessories and even hardware stores most people turn to a professional service.

Most professional window tinters would be up to date with the relevant State and Territory laws regarding the allowed ‘darkness’ of window tinting but car owners should also be aware of the laws. Especially, if they’re attempting a DIY window tint.

Like a lot of legislation related to vehicles, the States and Territories are not all equal in what they allow. Here’s what you need to know about window tinting and the law.

Factory Window Tinting

These days, when you look through the brochure of almost any new car you’ll see reference to privacy glass, sometimes it’s standard and sometimes it’s an extra-cost option. Privacy glass at the factory level is a dipped and dyed tint rather than a film-type tint, although the glass can also be dyed at the dealership level. Usually, to stick within the law, privacy glass has a VLT (Visible Light Transmission) of between 15-26%.

After-Market Window Tinting

This is type of window tinting involves a film being applied to the glass and this can be done by either by a trained professional or a handy DIYer. If you’ve ever covered a school exercise book with ‘contact’ or tried to put a screen cover onto a smartphone you’ll know that if you’re not extra careful when laying the film you’ll end up with bubbles in the surface.

Why tint your windows?

The most common reason people cite for wanting tinted windows is to keep the interior of their car cool and cut down harmful UV and UVB rays. But, according to the Cancer Council of Australia regular automotive glass cuts about 97% of UVB (short-wave ultraviolet light) which is the light that causes sunburn and more than 30% of UVA which is the sunlight that penetrates beyond the surface layer of your skin – it’s prolonged exposure to UVA that can lead to skin cancer. And laminated automotive glass is even more effective at cutting both UVA and UVB, indeed, it’ll cut down around 80% of UVA and it blocks UVB completely.

But what about keeping the interior of the car cool, does window tinting really help? According to a study by the RACQ in 2009 which explored the effects of windscreen sunshades and window tinting on the interior temperature of a car the temperature differences between them are minimal.

What the study revealed was that while clear automotive glass heats up quicker and with a higher interior temperature, but only by a few degrees C, than privacy glass and film-type window tinting, it was also quicker to cool if a shadow was introduced. The tinted windows took longer to reach ambient temperature and had a lower peak temperature than the clear automotive glass with the film-type tint recording a slightly lower peak temperature than the dye-type tint, but the difference was only 2 degrees C; the peak temperatures recorded were 59.7 and 61.8 degrees C, respectively.

What the RACQ study concluded was while tinted windows are slower to heat up than clear glass, the difference is almost so little that it’s almost not worth it. Especially when the fact that the windscreen is not allowed to be tinted and is thus significant entry points for both heat and glare. The study also showed that tinted windows slowed the heat loss from the interior of a car.

What are the rules around window tinting?

In Australia, regardless of where you live, the windows rear of the B-pillar can be tinted as can both the driver’s and passenger’s front window, but the VLT differs with the driver and passenger front windows requiring a greater light transference rate than the rear wiondows.

And, while it’s allowed to fit film-type tinting over the top of privacy glass, the combination of the two tints can’t exceed the allowed VLT (Visible Light Transference) for the State or Territory you live in, which is 35%, 20% or 15%. And aftermarket tinting cannot be applied to the windscreen, although a visor strip is allowed on the windscreen with each State and Territory having guidelines on how big this strip can be, it is generally allowed to cover 10% of the windscreen at the top only and it can usually be any colour. However, all window tinting, be it dye-type or film-type, regardless of where you live in Australia, cannot be more than 10% reflective.

The basic window tinting rules for Australia are (as of June 2018) for rear windows (B-pillar back):

35% VLT – Victoria and Tasmania have the strictest tinting regulations;

20% VLT – NSW, QLD, SA, ACT, WA now allows a darker tint;

15% VLT – Northern Territory allows the darkest tint in the country.

How hot does the interior of your car get?

Your car is, essentially, an unconventional oven. A car parked in the sun can become 20-30 degrees C hotter than the ambient temperature and 75% of that heat build-up occurs in the first five minutes and 90% in the 15 minutes. Leaving the window open (slightly – 1cm) has virtually no impact on reducing the interior temperature of the car.