The HTR Z5 is Sumitomo's Ultra High Performance Summer tire designed for the drivers of sports cars, sporty coupes and performance sedans looking for responsive high-speed handling and reliable traction in warm, dry and wet conditions. Like all Ultra High Performance Summer tires, the HTR Z5 is not intended to be serviced, stored nor driven in near- and below-freezing temperatures, through snow or on ice.An aggressive, summer compound is molded into the HTR Z5's asymmetric, five-rib tread pattern. A continuous center rib aids stability and improves steering response, while the substantial shoulders improve lateral grip. Notches in the intermediate and center ribs combine with the tread compound for traction in wet conditions, and the four wide, circumferential grooves and lateral shoulder grooves evacuate standing water from the footprint for hydroplaning resistance.The internal construction of the HTR Z5 consists of a two-ply, polyester casing supporting two high-rigidity steel belts. A full-width, nylon reinforcement ply improves high-speed stability, and a high-modulus bead insert strengthens the sidewall to aid handling. Note:Tires exposed to temperatures of 20 degrees F (-7 degrees C) or lower must be permitted to gradually return to temperatures of at least 40 degrees F (5 degrees C) for at least 24 hours before they are flexed in any manner, such as by adjusting inflation pressures, mounting them on wheels or using them to support, roll or drive a vehicle.Flexing of the specialized rubber compounds used in Ultra High Performance Summer tires during cold-weather use can result in irreversible compound cracking. Compound cracking is not a warrantable condition because it occurs as the result of improper use or storage. Tires exhibiting compound cracking must be replaced.