Avon Tire Storm 3D X-M Rear Tire (200/50ZR-17) High mileage sport touring tire. High performance plus extended mileage. The X-M version will deliver 15% - 20% extra mileage compared to the Storm 2 Ultra. The interlocking three-dimensional points hidden in the sipes to improve stability and grip (3D Sipes). High performance single and multi-compound super rich silica tread enhances wet grip (SRS).