Aquaplaning (or hydroplaning) occurs when a layer of water builds up under your tyres, seperating your car from the road surface and leading to a loss of control.
What is aquaplaning in a car?
Aquaplaning is one of the biggest dangers you can face when driving in wet conditions. It usually occurs at higher speeds when your tyres 'skim' over puddles or streams of water, rather than gripping the Tarmac underneath. When aquaplaning – also called hydroplaning – occurs, your car is essentially gliding without grip, leading to a loss of steering, braking and acceleration control – a bit like you've hit sheet ice. As such you won't be able to avoid other cars or motorway crash barriers, or stop a spin.
What causes aquaplaning?
Aquaplaning is caused by water on the road surface, either in puddles, thin layers of flowing water, or standing water from flooding. Aquaplaning happens when there is more water under a tyre than it can remove, causing it to lift up from the road surface and your car along with it. Tyre treads have deep grooves to channel water away from the surface of the tyre, allowing the tyre to grip the road – once there is more water than these grooves can cope with, you run the risk of aquaplaning.
From a driver's perspective, however, there are three main causes of aquaplaning:
- Driving too fast: This is the most common cause of aquaplaning and the one that's easiest to avoid. Driving too fast, and not adjusting your speed to match the conditions around you, can cause aquaplaning either during or following a rain shower. Excess speed in wet conditions might mean asking your tyres to deal with water on the road surface faster than they're able to, leading to your car aquaplaning.
- Not paying enough attention to conditions: It shouldn't be news to you that you need to take extra care in wet conditions, but being on the lookout for potential aquaplaning spots is an important extra step to remember. Puddles on the motorway are classic aquaplaning culprits and they can be hard to spot if the road surface already looks wet from rain. So make sure you keep an eye on the road surface ahead of you when the heavens open, and slow down if you see cars ahead of you splashing through huge puddles.
- Poor tyre condition: The grooves in your tyre tread are responsible for moving the water away from the tyre surface, but that tread wears away over time as you use your car. That means the grooves get progressively smaller and can't handle as much water as a result, increasing the risk of aquaplaning. This is why you need to replace your tyres when there's little tread depth left, so you know your tyres will perform properly in the wet.
How can you tell if your car is aquaplaning?
Modern cars do an awful lot to insulate you from the sensation of driving down the road, which means it can actually be a little tricky to know when your car is aquaplaning. However, there are a few signs you can look out for:
- Your steering wheel feels unusually light to turn
- Your engine noise and revs increase as your driving wheels lose grip
- You feel the car physically slow down as the drag from the water hits the tyres
- You hear a whooshing sound from the tyres as you hit the water
- You feel the front or rear of the car start to drift slightly
How to avoid aquaplaning
The single most important trick to avoiding aquaplaning is to slow down and match your speed to the conditions. This doesn't just mean rigidly following the speed limit, but actually being prepared to drive a lot slower than the posted limit if there's simply too much water on the road for your tyres to cope. Aquaplaning is especially likely on the motorway where traffic tends to move quite fast, so stay calm and don't feel rushed to match the speeds others are travelling at if you think it isn't safe.
You should also take extra care to watch the road ahead of you in wet conditions. Spotting a large puddle in advance gives you more time to react and to adjust your driving if needed. You should leave even more space between you and other motorists, too, to give you more room to avoid any dangers caused by aquaplaning.
For many safety reasons beyond just avoiding aquaplaning, you should keep on top of your vehicle's maintenance – servicing it in line with manufacturer intervals and making any running repairs needed to keep it working properly. That's especially true for tyres, which must have at least 1.6mm of tread depth across the middle three quarters of the tyres surface. If they don't, you run the risk of a fine, three penalty points or, in the worst case scenario, an accident.
What should I do if my car starts aquaplaning?
If your car does end up aquaplaning, you'll want to stay calm and be very gentle with your steering wheel and pedals to bring it back under control. First, hold your wheel straight and gently take your foot off the accelerator – if you have the cruise control turned on, make sure you turn it off. Avoid braking while your car is actually aquaplaning, as this can lead to a skid as the wheels suddenly regain traction.
After easing off the accelerator, your car will slow to a point where the wheels grip the road again. When this happens, you can then gently begin easing onto the brake pedal to slow yourself to a safe speed. Again, be sure to avoid stamping on the pedal harshly as this will upset your car's balance and might lead to a loss of control.
Tyre safety tips to avoid aquaplaning
As we've mentioned, it's crucial your tyres are in good condition when rainy weather hits (all year round in the UK, then…). Although by law your tyres must have at least 1.6mm of tread across the width of the tyre, that's a bare minimum, and we'd recommend replacing your tyres before then.
As well as making sure you have a decent amount of tread, check your tyres are inflated correctly. You'll find your car's recommended tyre pressures on the information label either inside the driver's door opening, or on the inside of your petrol flap. If you don't have a pump at home, use the air and water machine at your local petrol station to get back up to the right pressure.
Once that's done, make sure your tyres aren't wearing unevenly – this could be a sign of poor wheel alignment, which you can have fixed at your local garage. This is also a good time to check your tyres for bulges, punctures and any missing cuts to the sidewall – most of which will require a new tyre.
More top tips to keep you safe on the road
We have a selection of guides to help you stay safe on the roads. Take a look at our explainer for how to drive in heavy rain or learn more about driving safely in the snow. If you're a motorway regular, you might want to check out our guide to driving in high winds.
