In short, the main role is to increase the tire tread surface and road surface friction to prevent wheel spin, this exactly the same role with the sole pattern. Tread pattern improves grounding elastic tread, between the tread and the road surface tangential (such as driving, braking and lateral force) under the tread blocks can produce larger tangential elastic deformation. Tangential force increases the tangential deformation increases, contact surface "friction" also enhance and inhibit the tread and the road skidding or sliding trend. This is to a large extent eliminate free pattern (tread) drawbacks of tire skid, and tire and road surface friction performance of vehicle performance-power, braking, and steering control and safety play a reliable guarantee. Research shows that tread and road surface friction factors also include the adhesion between the two roles, gravity and road surface asperities on small size tread cutting effect, however, is the tread blocks play a major role in elastic deformation.