Pump sipes The pocket-shaped pump sipes on the tread blocks of the tyre's outer edges ensure good contact with the driving surface. Sipes are the cuts on the tyre tread. During the development of an earlier tyre model, Nokian Tyres patented the special pump sipes on the tread blocks of the tyre's shoulder area. For the new tyre, the operation of the pump sipes was further improved by increasing their volume. The pocket-shaped pump sipes remove, or rather pump, the water off of the surface of the road, ensuring thereby that the tyre maintains good contact with the driving surface. Together with the zigzag sipes, the pump sipes boost the tyre's wet grip and ice grip further. The even denser and sharper zigzag siping of the aggressive tread pattern improves the grip that is needed in extremely slippery weather and in deep snow. The wider single sipes provide more grip for rough ice and snow. The heavily grooved surface and open block gaps in the shoulder area have excellent self-cleaning characteristics in snow and slush.