New research shows that while 83% of drivers believe they are in full control of their vehicle’s stopping distance, only 6% can correctly identify how much extra distance is needed to stop in wet conditions at motorway speeds. In reality, stopping distances can increase dramatically in the rain—yet 94% of drivers underestimate this risk, with many misjudging by significant margins.
At motorway speeds (70 mph), having tyres worn down to the legal minimum of 1.6mm can add around 27 metres (6 car lengths) to your stopping distance in the wet compared to what the Highway Code predicts.
- 2-Second Rule (Dry Conditions): Leave at least a 2-second time gap between your car and the vehicle ahead on normal, dry roads.
- 4-Second Rule (Wet Conditions): Double the time gap to at least 4 seconds when driving in the rain or on wet, slippery roads because braking distances increase.
How to Measure the Gap
- Pick a fixed marker ahead, such as a lamppost, bridge, or road sign.
- Wait for the car in front to pass that marker.
- Count the seconds (e.g., “one thousand and one, one thousand and two” for two seconds, or up to four seconds for wet weather).
- Check your position: If your car passes the same marker before your count finishes, you are following too close and need to slow down or drop back.
On icy or snowy roads, you need to increase your following distance to a 20-second gap.
