Battlax S21 S21 is a fantastic combination of proven S20EVO wet technology and radically new features that take dryness performance to a whole new level. Excellent cornering behavior: The superior stability of the S21 enables faster cornering acceleration and retraction, as well as more accurate lane keeping, so you can drive smoothly without any loss of power. High mileage: For top-notch handling performance, you do not have to sacrifice tire life. S21 comes up to 36% higher mileage than its predecessor. Advanced tread design and Bridgestone's latest rubber blending technologies give you the peace of mind you need in wet conditions.