The three tests answer three different questions
Wet braking
How the tyre slows the car while maintaining contact with the road.
Straight-line aquaplaning
When a wedge of water starts lifting the moving tyre in a straight line.
A flooded bend
How the tyre maintains lateral contact under cornering load.
The chart does not compare models and does not indicate a safe speed. It separates braking on wet asphalt, linear aquaplaning and grip in a flooded corner.
Source: Tyre Reviews test methodology; checked 2026-08-07.
Three different wet road tests
| Test | What is measured | What the result tells you | What it does not tell you |
|---|---|---|---|
| Wet braking | Braking distance or deceleration in a controlled water layer | How effectively the tyre transfers braking force to wet tarmac | When the tyre will aquaplane in a deep rut |
| Straight-line aquaplaning | Speed at which the wheel in water reaches a defined slip threshold | Resistance to aquaplaning through a controlled water trough in a straight line | Lateral grip in a flooded bend |
| Lateral aquaplaning | Critical speed or loss of lateral force in a flooded bend | How the tyre maintains lateral contact under cornering load | Everyday braking distance on a thin water layer |
| Wet handling | Lap time, balance and driver control on a continuously wetted track | Overall cornering and transitional behaviour | The isolated emergency braking or deep-water threshold |
In the Tyre Reviews methodology, wet braking is measured by GPS equipment, and for linear aquaplaning, one side of the car drives through a trough of water with a controlled depth of about 7 mm. The cornering test separately measures the limit at which lateral grip is lost in a wet corner. Therefore, a single overall "wet road score" can hide an important trade-off for the driver.
What the wet grip class of the EU label shows
Under Regulation (EU) 2020/740, the new tyre label gives a wet grip class from A to E. This standardised index for a particular tyre type is useful for an initial comparison. The label does not separately rate straight-line or lateral aquaplaning, wet handling or performance as the tread wears.
What is the risk of aquaplaning?
- Water depth: The thicker the water layer, the lower the speed that can be sufficient to lose contact.
- Speed: As speed increases, the tread has less time to remove water from the contact zone.
- Tread Depth and Tread Pattern: Shallow or unevenly worn grooves hold and direct less water.
- Tyre pressure: Both under- and over-inflation change the contact patch and can increase risk.
- Tyre width: other things being equal, a wider tyre needs to displace more water, but you can't arbitrarily choose a size that's not allowed on the car.
- Road: Ruts, poor cross slope and puddles can create a much deeper layer than on the test track.
ADAC states that in their 7 mm water depth test, new tyres of around 8 mm initial tread often start floating at around 75–85 km/h, while narrow 155 mm tyres can exceed 90 km/h. This is not a safe speed for a public road: the real puddle may be deeper, the tyre more worn, the pressure is not correct, and the cornering creates additional side load.
How to reduce risk before entering a puddle
- In heavy rain, reduce your speed before you reach ruts or visible puddles.
- Increase the distance to the car in front and avoid sudden braking or changing direction.
- Watch for splashes of water, ruts and changes in wheel noise - these can be warning signs of a thickening layer of water.
- Regularly measure the tread across its entyre width and check the pressure specified by the car manufacturer.
- Don't think of ABS, ESP or all-wheel drive as skid protection: the electronics need mechanical contact with the road.
What to do if the car has already started to float
- Keep the steering wheel still and as straight as possible; don't spin it suddenly looking for traction.
- Release the accelerator gently, but avoid sudden engine braking.
- Do not brake suddenly or accelerate until the wheels regain contact.
- Do not change the automatic transmission mode while aquaplaning.
- When contact returns, adjust speed and direction gradually after assessing surrounding traffic.
How to choose a tyre for frequent rain
Look beyond a high EU wet grip class. In an independent test of the same size, compare wet braking distance, the critical speed for straight-line aquaplaning, lateral aquaplaning performance and wet handling comments. A source without these tests cannot establish complete wet-road safety.
Frequently asked questions
Does wet grip class A mean the best aquaplaning resistance?
No. The EU label gives a standardised wet grip class but no separate aquaplaning score. Check straight-line and lateral aquaplaning in independent tests.
At what speed does aquaplaning start?
There is no universal speed. Water depth, tread, pressure, width, road shape, load and cornering all affect the threshold. A controlled test result is not a safe-speed recommendation for public roads.
Can ABS and ESP stop aquaplaning?
No. They cannot restore tyre-road forces when a layer of water separates them. They can help once some or all wheels regain contact.
Is a wider tyre always more dangerous in rain?
Other things being equal, a wider tyre must displace more water. Tread design and the size variant strongly affect the result. Do not fit an unapproved size based on this general tendency.
Which test figure matters most in water-filled ruts?
Start with the critical speed for straight-line aquaplaning. For frequent bends or lane changes, also check lateral aquaplaning. Wet braking distance answers a different, equally important question.