Dunlop Sportmax GPR-300 Rear Tire (140/70R17) Introducing Sportmax GPR-300 - The Sportmax&#174; GPR-300 is a radial tire that offers well-balanced sport performance for a variety of sport bikes. Value: Designed to offer a balance of performance and value. Handling: Because bikes are meant to lean over. Radial tire technology helps to provide enhanced grip in wet and dry conditions. Optimized construction to enhance handling and responsiveness for street-going sport riding.