Centerlock wheel

Initially called "QD" (for "quickly disconnectable") the basic mechanism for "knock-off" style centerlock hubs was patented by 1908.

[2][3] In 1922, Carlo Borrani licensed the Rudge-Whitworth "knock off" wheel and hub design and started his own company to manufacture them.

Early customers for Borrani wheels included Alfa Romeo, Isotta Fraschini, Fiat, Lancia, Porsche, Mercedes-Benz and Auto Union.

[2][3][4] In the late 1960s, road car safety regulations in the United States and Germany led to the removal of the distinctive wings or "ears" from knock-off hub nuts.

[6] Centerlock wheels and hubs continued to be used for racing cars, although the mechanical details of the design gradually changed from the original Rudge-Whitworth pattern.

[5][2][3] The visual appearance of the knock-off nut was incorporated as a styling element on spinner hubcaps, primarily used on American cars.

In particular, Porsche has developed a proprietary center locking design for use on race and road cars such as the RS Spyder and the 911 Turbo.

FIA rules also mandate an additional locking mechanism be included in F1 centerlock hubs, which manufacturers have implemented in different ways.