These flanged rims are made of polished 6051-T6 aluminum and are therefore extremely light. Harley-Davidson gained access to European high-performance components such as Dell'Orto carburetors, Oldani brakes and Borrani aluminum rims by acquiring a majority stockholding in Aermacchi in the 1960s. After such parts were initially installed on KR series race bikes, it wasn't long before the first production Sportster was offered with such flanged alloy rims. These SWC rims are reproductions of the parts from this era.