The HTR Z II (High Technology Radials-2nd generation) is Sumitomo's Ultra High Performance Summer tire developed for the drivers of sports cars, sporty coupes and performance sedans. The HTR Z II is designed to blend a unique appearance, dry and wet performance and ride comfort. Like all summer tires, the HTR Z II is not intended to be driven in near-freezing temperatures, through snow or on ice.The HTR Z II molds a high performance tread compound featuring ultra micro carbon technology and silica-based rubber into a directional pattern that features wide, arched tread blocks to enhance dry road traction and handling. A circumferential center rain groove and multi-direction water channels resist hydroplaning and enhance wet traction. The tire's internal structure features two steel belts with spirally wrapped Jointless Nylon Band reinforcement to enhance high-speed durability while minimizing weight and improving ride uniformity. The lower sidewall features Single Strand Beads for improved wheel fit and Wheel Flange Guards to help protect alloy wheels from accidental curb damage.Note: Sumitomo reassessed the HTR Z II line's UTQG ratings in 2009. This resulted in tires featuring the same design, materials and manufacturing methods previously rated 220 AA A to be assigned UTQG ratings of 360 A A. Sumitomo has confirmed that regardless of the branded UTQG ratings, all HTR Z II tires are fully compatible and may be mixed individually or in pairs as necessary.