If the tread pattern, i.e. the arrangement of the top layer of rubber, is "V" or "U" shaped, we can usually speak of directional tyres. This is characterised by diagonal grooves that converge towards the centre of the tread.
An extremely important issue with directional tyres is their correct fitting. The rolling direction of the tyre (indicated by an arrow or the wording "ROTATION") must always be aligned with the direction of travel of the vehicle.