Skids and aquaplaning

By the end of this topic you can

• You can explain what causes skids and aquaplaning.
• You can drive smoothly on wet, icy and loose surfaces to avoid a skid.
• You can recognise the early signs of a skid or aquaplaning.
• You can respond calmly by easing off and steering where you want to go.
• You can use ABS brakes correctly in an emergency stop.

What you need to know and understand

• Most skids are caused by too much speed, harsh braking, harsh acceleration or sharp steering for the conditions.
• Worn tyres and incorrect tyre pressures greatly increase the risk of skids and aquaplaning.
• The legal minimum tread depth for car tyres is 1.6 mm, but more tread gives much better grip in the wet.
• When aquaplaning, the steering may suddenly feel light.
• With ABS, press the brake firmly and keep pressing. You can still steer.
• Braking distances are much longer on wet and icy roads.

What makes a car skid

• Braking too hard, so the wheels lock (in a car without ABS).
• Accelerating too hard, so the driven wheels spin.
• Steering too sharply or too fast for the speed.
• Going too fast into a bend, especially downhill.
• Slippery surfaces: ice, snow, wet leaves, mud, diesel spills, loose chippings and painted road markings in the rain.
• Poor tyres, wrong pressures or an overloaded car.

If the car starts to skid

1. Stay calm and look where you want the car to go, not at what you are afraid of hitting.
2. Take your foot off the accelerator to reduce the cause.
3. If you are braking and the car has no ABS, release the brake enough to let the wheels turn again.
4. Steer smoothly in the direction you want to go. If the back of the car slides to the left, steer gently left.
5. Be ready for the car to swing the other way as grip returns, and correct gently.
6. If the car has ABS and you need to stop, brake firmly, keep the pressure on and steer round the danger.

Standing water and aquaplaning

Aquaplaning happens when water builds up in front of the tyres faster than the tread can clear it. The tyres lift off the road and you lose steering and braking. It is more likely at higher speeds, in heavy rain, on worn tyres and where water collects in dips and at the edge of the road.

If the steering suddenly goes light, do not brake hard or steer sharply. Ease off the accelerator gently, hold the wheel straight and let the car slow until the tyres grip again. The best defence is to slow down when you see standing water ahead and drive through it gently.

Common mistakes

• Slamming on the brakes when the car slides. Ease off and steer smoothly instead.
• Pumping ABS brakes. Keep firm, steady pressure and let the system work.
• Driving at normal speed through standing water. Slow down before you reach it.
• Ignoring worn tyres. Check tread and pressures regularly.
• Overcorrecting with big steering movements. Small, smooth inputs work best.

Test yourself: Skids and aquaplaning

Answer each question, then read the explanation. Questions come in a random order each time.