Aluminum alloy wheels used in the automotive industry are generally castings produced in permanent molds. The alloy used is 356 or A356 (Aluminum Association designation). They are usually given a T6 heat treatment, which means that they are solution heat treated, then quenched, then artificially aged. A typical heat treatment schedule would look like this:
Solution heat treat at 540 C for 4-12 hours
Quench into hot water: ~ 65-100 C
Artificial aging treatment is usually 155 C for 3-5 hours