How to avoid hydroplaning in the rain: Why tyre tread matters

When a car travels too quickly through standing water, the tyres may not be able to clear the water from the road quickly enough. The tyres can then lose direct contact with the road surface and ride on a layer of water instead. This is known as hydroplaning, or aquaplaning.

Why is hydroplaning more likely in the rain?

Tyres can only clear so much water: The actual contact patch between a tyre and the road is surprisingly small — roughly the size of four postcards. When there is standing water on the road, the tread grooves have to act like tiny pumps, quickly pushing water out to the sides and behind the tyre.

Water pressure can lift the tyre: As speed increases, the tyre can enter the standing water faster than the tread can clear it. This creates a high-pressure wedge of water in front of the tyre. Once the upward force from the water becomes equal to the downward force acting on the wheel, the tyre can start to float on the water.

Grip can disappear: Once hydroplaning begins, steering, braking and drive traction can be severely compromised. The steering wheel may suddenly feel unusually light, with very little feedback, and the car can become difficult to control.

Why does tyre tread depth matter?

Tread is not just there for looks. Those grooves are the tyre's main route for clearing water, and tread depth has a direct impact on how well a tyre can resist hydroplaning.

Less space for water: New tyres have deeper grooves that can hold and channel away more water. As the tread wears down, the grooves become shallower and their ability to clear water drops significantly. At higher speeds, they can quickly become overwhelmed by standing water.

Less ability to cut through water: Worn tread is less effective at cutting through and displacing the layer of water on the road. This can lower the speed at which hydroplaning occurs. A worn tyre that might only start to lose grip at around 80km/h when new could potentially become unstable at around 60km/h once heavily worn.

The legal safety limit: International standards and Malaysian regulations generally require tyres to be replaced when the remaining tread depth falls below 1.6mm. For safer driving during the rainy season, however, it is worth considering replacement once tread depth has worn down to around 2–3mm.

How to reduce the risk of hydroplaning

Slow down: The faster you drive, the less time the tyres have to clear standing water, and the risk of hydroplaning rises sharply. In heavy rain, slow down proactively, particularly when driving on motorways.

Avoid sudden steering or braking: Try to keep the car travelling in a straight line through flooded sections and slow down before reaching them. Avoid making sudden steering inputs or stamping on the brakes while driving through standing water.

Do not use cruise control: Using cruise control in heavy rain can make a hydroplaning incident more dangerous. If a tyre suddenly loses grip, its wheel speed can change rapidly, potentially causing the system to respond in a way that increases the risk of losing control.