How wet roads give grip the slip.

ITALY; GERMANY

This article reports that a team in Italy and Germany has come up with an explanation that could make wet-weather driving safer. A vehicle on wet a road typically requires double or triple its normal stopping distance, and skids more easily. If the road is flooded or the vehicle is travelling faster than 60 kilometres per hour, the cause is usually aquaplaning, which occurs when the tyre is moving too fast to flush water from the road beneath it. But aquaplaning does not explain the loss of grip at lower speeds, which measurements have shown can fall by as much as 30 per cent compared with the grip in the dry. One suggested explanation is that water forms a partial barrier between the tyres and the road; another that the water weakens the bonds that form briefly between the molecules in the tyre and road.