It’s a bit of a no-brainer that worn tyres decrease the safety of your car – but how much exactly? The tread depth of your tyres makes a big difference to your car’s handling, cornering and, most importantly, its stopping ability – especially in wet conditions. There is a legal minimum depth for tyres, which will come up in your Warrant of Fitness check but it’s good to understand the risks in having worn tyres. So, here’s an example of how tyre tread can affect stopping time.
Car A has a full set of new tyres and is driving at 80km/h in wet weather. They see a hazard and slam on the breaks to make an emergency stop. Car A comes to a stop comfortably and has reduced risk of aquaplaning (when a wedge of water can build up between the tyre and the road surface).
In comparison, the same situation happens to Car B, who has 3.0 mm tread depth (well within the legal limit). It takes Car B 9.5 metres longer to come to a stop and at the point where Car A stopped, and Car B is still travelling over 30km/h at this point.
Then, we consider Car C, with the minimum legal tread depth of 1.5mm tread depth. This car takes an additional 18.6 metres to come to a stop and will be travelling over 40km/h where Car A stopped and 30km/h where Car B stopped.
Another way to think of it is in car-lengths. If the average Kiwi sedan is about 5m in length, then it’s nearly two full car-lengths needed to stop with 3.0mm tread depth, and just over three-and-a-half car-lengths to stop with 1.5mm tread depth.
It’s quick and easy to check your tyre tread depth. You can either get yourself a tyre tread depth checker (see below), or you can ask your local garage to check it for you.
This article is intended to provide general information only, and should not be substituted for any legal, financial, or other professional advice. The information in this article is generally sourced from third-party websites and IAG New Zealand Limited does not guarantee or accept any liability for the accuracy of that information. Any references to third party websites in this article are not intended to constitute a recommendation or any endorsement by IAG New Zealand Limited.
