ROH uses CC601 aluminium alloy cast using the low pressure process for all our alloy wheels. This alloy consists of pure Aluminium with controlled percentages of Silicon, Magnesium, Titanium, Stronium and other key elements. The wheel castings are heat treated to the T6 specification. T6 heat treating is a process in which the alloy is heated to above 500° in an oven, and held at that temperature for an 8 hour period to allow a certain constituent to enter into solid solution, and is then cooled rapidly to hold that constituent in solution. This makes the alloy soft and ductile. The metal is then artificially aged which is a time-temperature-dependent change in the properties of the alloy making it harder. These two processes together causes the structure of the wheel to change, resulting in increased strength and toughness.