One-way street

THE tread on directional tyres is designed to flush water forward or to the sides of the contact patch when run in a particular direction. It is claimed they are more efficient at removing water from the contact patch than tyres that can run in either direction. It's been common for carmakers to fit directional tyres, but some in the tyre business believe it's more about marketing than real function. They point to a trend back to asymmetrical treads. The tread on asymmetrical designs moves water to the inside of the tyre, leaving the outer shoulder dry for better grip when cornering. Ford has replaced a directional tyre on its XR sports models with an asymmetrical tyre.