Safety First: how to brake on wet surface

When adherence reduces, driving behaviour needs to be adjusted accordingly. Guidelines for tackling wet conditions safely

Home road cars tips Safety First: how to brake on wet surface

Never panic when you are driving a vehicle on wet roads and take greater care. Despite the fact that modern cars provide a great deal of help to drivers, even compensating for potential mistakes, it is always preferable to be aware of the best driving techniques. This is because rain, puddles and a wet road surface are factors which have an impact on a vehicle and which can also cause aquaplaning.

This phenomenon occurs when water accumulates in front of the tyres more rapidly than the rate at which the weight of the vehicle is able to disperse it. This creates water pressure underneath the tyre and the formation of a thin layer of water between the tyre and the road surface. The deeper the water and the higher the speed of the vehicle, the greater will be the risk that this phenomenon will occur. And obviously in the absence of any adherence to the road, it becomes impossible to steer or brake the vehicle correctly.

The importance of the depth of the tyre tread

The first adjustment required for driving in the wet is to know how to calculate the stopping distance, which is greater when the road surface is slippery. The advice is to double the normal safe braking distance and, furthermore, to multiply it by ten when there is a risk that the road surface is icy.

The correct tyre tread depth is of fundamental importance. Suffice it to say that with 8 mm of tread depth, the stopping distance from 80 km/h to 0 for a “normal” car is 42.3 metres, whereas going down to a tread depth of only 3 mm you require 51.8 metres. And with just 1.6 mm, you need 60.9 metres to come to a stop, which is nearly 20 metres more.

Another factor to be taken into consideration – indeed this is always valid and not just in the wet – is tyre pressure. If your tyres are over-inflated, or under-inflated, they could become worn in an irregular fashion, resulting in uneven adherence during braking. 

A matter for your foot

In order to slow down on wet surfaces, it is important to ensure you have the right “feel” with your foot. In practice, without using excessive force, you must “accompany” the pedals during manoeuvres in such a way as to avoid blocking the wheels and losing directional control. If the tyres begin to lose adherence, you should lift your foot off the accelerator and avoid braking or swerving. The correct behaviour is to depress the clutch pedal or to select transmission position N – if the clutch is automatic - in order to reduce your speed until you can once more take full control of your vehicle.

The transmission of power is fundamentally important

When you need to brake and swerve – for example in order to avoid an obstacle on a straight road – it is advisable to brake decisively for as long as you can travel straight ahead, then to lift your foot off the brake pedal in order to allow renewed power transmission to the wheels, enabling you to modify your trajectory. It is only at that point that you can start to brake decisively again in order to maximise the braking effect.

If on the other hand you find that you have entered a bend too quickly, in order to slow down you need to use the brake pedal (in this case, with extreme delicacy) and you must categorically avoid depressing the clutch pedal: if you remove the “pulling power” of the engine from the wheels, you will be unable to regain control of the vehicle, and indeed the tyres will no longer be correctly balanced and will skid immediately.