Aquaplaning and heavy rain – important tips

Cars in heavy rain and aquaplaning tests.

Risk of aquaplaning in heavy rain

GTÜ tips for defusing dangerous situations

Tires with a good tread significantly reduce the risk

Hectic driving maneuvers can cause the car to skid

A sudden onset of heavy rain changes road conditions dramatically: puddles of water on the road in dips and ruts can cause aquaplaning.
Basically, the higher the water level on the road and the higher the speed, the more likely a vehicle is to float.
The tires lose contact with the road surface, similar to driving on slippery ice.
Steering and braking have little or no effect.
Tires with a lot of tread significantly reduce the risk of aquaplaning.
If you react correctly at the wheel in this critical situation, you also reduce the risk of uncontrolled skidding.
The GTÜ Gesellschaft für Technische Überwachung mbH recommends that you always bear in mind the context of aquaplaning.
Five tips from GTÜ on the subject of aquaplaning:

1. it all depends on the tires: Heavy rain, ruts in the asphalt, high speed and wide tires close to the permissible tread limit – with these ingredients, aquaplaning is almost inevitable.
How can the danger be reduced or avoided?
Keyword tires: A lot of tread helps a lot.
The better it is, the faster the water is drained away through the grooves in the rubber.
The law stipulates that summer tires for cars and motorcycles must have at least 1.6 millimeters of tread.
However, this only protects against a fine, not against the vehicle floating.
GTÜ recommends at least four millimeters of tread rubber on the tread for summer tires.
New tires have a tread depth of about eight millimeters.
Depending on driving style and mileage, they offer good safety for many years.
In addition, the wider a tire is, the less water it can displace.
Too low or too high tire pressure also increases the risk of floating.

2. reduce speed: Adapting your speed reduces the risk of aquaplaning.
It is not for nothing that many “80 km/h in wet conditions” signs on highways demand a maximum speed adapted to the situation.
GTÜ also recommends this speed as a rule of thumb for safe driving on wet roads.
However, if it is raining so heavily that the windshield wipers can barely get the water off the windshield, this speed is also too high.
If there is also standing water in some places, you may even have to drive at walking pace or stop briefly in a parking lot until the rain subsides.

3. read the road: A concentrated look at the road surface provides some indications of impending aquaplaning.
Standing water in depressions or ruts changes the gray tone of the asphalt surface or is even reflected.
The same effect also occurs in headlights in the dark.
Heavy spray from cars in front is also a clear indication of a lot of water on the road.
And if the tire tracks of cars in front blur on wet asphalt, there is a lot of water on the road.
Ruts can be avoided by driving slightly off-center.
If the water is in depressions, it is almost impossible to avoid driving through it.

4. brake and steer as little as possible: When aquaplaning, the car loses contact with the road.
The driver feels “very light” steering.
Sometimes the electronic stability program (ESP) indicator light flashes and the engine speed increases audibly.
Now it is important to remain calm.
The car can no longer be fully steered.
However, it will continue to glide in the same direction.
Hold the steering wheel firmly and do not move it.
The wheels usually regain grip after a few seconds and the danger is averted.
If you have steered after all, things can get dicey: The wheels are then positioned differently to the original direction of movement.
If the wheels regain grip, the vehicle will turn in the new direction – with a high risk of skidding.
It is also better not to touch the brake pedal.
At the same time, it helps to take your foot off the accelerator slowly to avoid load change reactions.
In vehicles with a manual gearbox, depressing the clutch counteracts the effects of the “engine brake”.
These tips also apply if only two wheels are floating.
The anti-lock braking system (ABS) and ESP, which are widely used in modern cars, do help, but the varying grip of the individual tires can still throw the car off course.

5. insurance: In the event of an aquaplaning accident, first secure the accident site and call for help, in the worst case the emergency services.
If you have fully comprehensive insurance, the insurance will also cover the damage to the vehicle of the person who caused the accident.
There is one exception: If the police determine during the accident investigation that the tread depth is less than the legally prescribed 1.6 millimetres, this can be considered gross negligence and the fully comprehensive insurance may not cover the damage.
As a general rule, liability insurance only pays for damage to the property of others.