Aquaplaning: tread depth impacts driving safety

Tyre manufacturer Nokian Tyres explains what to look out for during the rainy season and why just a few millimetres of tread can make all the difference.

Aquaplaning is a real threat in rainy weather. As soon as the tread is unable to drain all the water away from the point of contact between the tyre and the road, a water cushion forms under the tyre. This causes the tyres to lose their grip and the driver loses control of their vehicle.

"In this situation, the driver can become a helpless passenger with no control over his/her vehicle in an instant. However, the most important thing is to keep calm and not brake suddenly. It’s best to take your foot off the accelerator, let the car slowly reduce speed and keep a close eye on the direction of travel. As soon as you feel the tyres regain contact with the road, you can gradually start to accelerate again", says Martin Dražík, Product Manager for Central Europe at Nokian Tyres.

There is a real risk of aquaplaning even with good tyres, but it’s almost certain with worn ones. That’s why it’s important to be aware of the condition and quality of the tyres on your car.

As a rule of thumb, the smaller the tread depth, the more likely the tyres will lose their grip on the wet road. Therefore, driving on worn tyres is a major risk, especially in the rain, when the braking distance is significantly longer. You thus become a danger not just to yourself, but to everyone around you.

Drivers who have put off purchasing new tyres should pay even more attention to the proper maintenance of their current ones, so that their safety features last as long as possible.

The risk of aquaplaning can be reduced by using tyres with a tread of at least 4mm. As soon as tread depth falls below this figure, your protection from this dangerous phenomenon deteriorates significantly. The correct tyre pressure is also important.

"Our tyres have several innovations that simplify safe driving and tyre condition monitoring. One of these is the patented Driving Safety Indicator that allows the driver to immediately see how many millimetres of tread are remaining of each individual tyre with their naked eye", adds Dražík.

It’s important to anticipate dangerous situations

Heavy rain and poor tyre condition are a bad combination. Similarly, driving too fast in bad weather makes your vehicle more prone to aquaplaning, even if you have good tyres. In heavy rain, speed may need to be reduced by as much as 15-20km/h so that the tread can pump away all the water between the tyre and the road.

 “I don't understand why so many people drive in ruts on the road even when it's raining. This is exactly where the risk of aquaplaning is highest. Driving in ruts also wears down tyres faster because the asphalt is much rougher there. That's another reason to drive outside of ruts," remarks Martin Dražík from Nokian Tyres.

Tests carried out by Finnish magazine Mootori (03/2020) showed that worn tyres started aquaplaning at a speed as much as 15km/h earlier than new tyres.

For the best tyre tested, the new tyre started aquaplaning at 90,4km/h while a tyre worn down to just 3.5mm already started aquaplaning at around 75km/h.

In addition to tread depth, tyre pressure should also be checked. Low pressure increases the risk of aquaplaning. Checking your tyre pressure and adjusting it to the correct level, if necessary, is a basic safety measure that you can take at your nearest petrol station and it doesn’t cost a thing.

Tips for dealing with the risk of aquaplaning

• Check the condition of your tyres before every trip, maintain a sufficient tyre pressure and make sure that tread depth is at least 4mm to ensure driving safety.
• Check the weather report before driving and anticipate dangerous situations, these include heavy downpours or thunderstorms.
• Do not drive in ruts on the road in the rain.
• Reduce your driving speed by at least 20km p/h during heavy rain and downpours.
• Keep sufficient distance to vehicles in front of you.
• If aquaplaning occurs, stay calm, take your foot off the accelerator, and let the car slow down until you feel contact between the tyres and the road again and maintain your direction of travel.