SSR Professor SP5 wheels are true three piece wheels made in Japan. After the SSR SP5 wheels are made, they go through a spinning process during manufacturing. They are heat treated for a second time. This application of heat increases the strength of the wheel. As a result the wheels are lighter and stronger making them ideal for hard tuned race cars and heavier vehicles. The SSR Professor SP5R wheels are available in 18", 19", & 20".