Expert advice: car window tinting. All you need to know

Tinted windows or privacy glass are becoming an increasingly popular option for new car buyers. But if you decide to have the windows of your existing car tinted, you have to be really careful. The law is strict about car window tinting. And rightly so because excessively shaded glass can reduce a driver’s ability to see in the dark. It can also prevent drivers confirming through eye contact that they’ve seen other road users and pedestrians.

Although the tint of car windows isn’t part of the MOT test, you could still end up breaking the law and invalidating your insurance. Here’s what you need to be aware of.

Which windows does it apply to?

First of all, let’s be clear (sorry!): the law around tinted glass applies to the windscreen and front side windows only. There are no rules when it comes to tinting rear windows or the rear screen. Otherwise millions of panel van and limousine drivers would have no choice but to break the law.

What is the law around car window tinting?

Illegally tinted glass can jeopardise the safety of all road users. The last thing we want on the road is drivers who can’t see out properly. For cars registered before April 1, 1985, the front screen and front side glass must let at least 70 per cent of light through. For vehicles registered after that date, the windscreen must let at least 75 per cent of light through; the front side windows 70 per cent.

What about buying a car with tinted glass?

A car maker will never knowingly fit glass that’s illegal. If you’re buying a new car, there should be no problems. If it’s a second-hand car and the glass is heavily tinted you need to be careful. It’s actually against the law to sell a car with illegally tinted front glass because it doesn’t comply with Construction & Use Regulations. If you’re in any doubt, walk away or ask the seller to remove the tint at their cost.

What about insurance?

As with any modification, insurers need to know. Whatever the change people are making, I always advise them to ask their insurer beforehand. It’s an easy way of preventing any unpleasant surprises. You must tell your insurer even if you’re tinting rear glass to improve security or protect young kids from the sun. The message is: tinting glass may affect your premium or the ability to get cover.

And if you decide to go ahead anyway?

It’s illegal for any company to supply glass or window tinting film for front windows that doesn’t comply with Construction & Use Regulations when fitted to the vehicle. Should you fit illegally dark tinting film, police or the Driver and Vehicle Standards Agency may check it using special light measuring equipment. If the windscreen or front windows are deemed to be too tinted, you could be banned from using the car until the film is removed. In extreme cases you could get a penalty notice or court summons.

Why isn’t it part of the MOT?

You might be surprised to know that tinting glass isn’t part of the MOT test. This is because of the 24 million or so cars that go through the MOT every year, only a tiny proportion have tinted glass. And some MOT test centres may never see a car with windows darkened by the owner. If every garage invested in the necessary equipment to measure the tint of glass, the price of everybody’s MOT would have to rise. And that isn’t something I suspect the majority of car owners would be particularly happy about. I certainly wouldn’t be.

Nick Reid is head of automotive technology for Green Flag and is a fellow of the Institute of the Motor Industry