Wet Motorway, Aquaplaning and a Faded Tyre
You are driving on a three-lane motorway at 120 km/h in heavy rain. The speed limit is 130 km/h. Your front tyres have about 2.5 mm of tread in the centre and 1.8 mm at the edges; the legal minimum is 1.6 mm. Water is pooling in the wheel tracks, and you feel a brief lightening of the steering and a slight rise in engine speed without acceleration. A lorry ahead is throwing up heavy spray, and a car is overtaking you on the left. Visibility is about 100 m, and your wipers are on full speed.
1. What is the warning sign, what is happening, and what is the immediate correct response?
Read the worked answer
The lightening of steering and the rise in engine speed without acceleration are classic early aquaplaning signs: the tyres have lifted onto a film of water and lost contact with the road. The worn tread (2.5 mm centre, 1.8 mm edges, close to the 1.6 mm legal minimum) cannot clear water fast enough, so the risk is high.
Immediate response:
- Ease off the accelerator smoothly; do not brake hard.
- Hold the steering straight and avoid sudden inputs; a correction while the tyres are unloaded can cause a spin once grip returns.
- Do not change lanes, especially not toward the overtaking car on your left.
- Let speed fall until you feel steering weight return, then reduce to a speed suited to the conditions, perhaps 80–90 km/h.
Braking or steering during the aquaplane can cause loss of control. Once grip is restored, reduce speed and increase the gap to the lorry so its spray does not blind you.
2. How should you manage the remaining journey, and why is the tyre condition decisive?
Read the worked answer
Treat the tyres as the decisive factor. Tread at 1.8–2.5 mm is legal but poor in standing water; water clearance falls sharply as tread depth drops, so aquaplaning recurs at lower speeds. The correct decision is to leave the motorway at the next exit and replace the front tyres, or at minimum reduce speed substantially and avoid the wheel-track pools.
For the rest of the journey:
- Reduce speed to a level where you can stop within the visible distance, roughly half the speedometer reading in metres on wet roads.
- Increase the following gap to at least four seconds, more behind the lorry.
- Use dipped headlights, keep the windscreen demisted, and avoid cruise control so you can react instantly.
- Stay out of the deepest wheel tracks where possible and avoid sudden lane changes.
If the aquaplaning recurs, stop at a safe place and wait for the rain to ease rather than pressing on.