As tire designers the Ultremo is the pinnacle of our ambition. We strived relentlessly to increase its speed and installed the ZX with HD Speed Guard and RaceStar Triple Compound. Both components are perfectly tuned to the requirements of an outstanding competition tire. The result: Significant reduction in rolling resistance. Even so we used additional material to reinforce the tire shoulders and to ensure a considerable increase in mileage. ZX - the best Ultremo ever!