Bridgestone Battlecross X31F Tire - 90/100-21 57M FrontThe BATTLECROSS X31 is for a broader range of intermediate terrain in big bike sizes. Starting where the X30 left off, the X31 is enhanced with Bunker Groove technology which results in greater traction in both harder and softer terrains. Bunker Groove works by improving casing flex which enhances traction in harder terrain and adds biting edges for traction in softer conditions. Cooling Fins keep the feel consistent throughout your moto