Alloy wheel
Alloys of aluminium or magnesium are typically lighter for the same strength, provide better heat conduction, and often produce improved cosmetic appearance over steel wheels.
Although they lost favor on common vehicles, they remained popular through the 1960s, albeit in very limited numbers.
Alloys allow the use of attractive bare-metal finishes, but these need to be sealed with paint or wheel covers.
Even if so protected the wheels in use will eventually start to corrode after 3 to 5 years but refurbishment is now widely available at a cost.
Alloy wheels are prone to galvanic corrosion, which can cause the tires to leak air if appropriate preventive measures are not taken.
The high cost of alloy wheels makes them attractive to thieves; to counter this, automakers and dealers often use locking lug nuts or bolts which require a special key to remove.
Research by Car and Driver conducted using a selection of differently sized alloy wheels from 16 to 19 in (41 to 48 cm) all outfitted with the same make and model of tires showed that both acceleration and fuel economy suffered with larger wheels.
[6] In fact, US Federal Aviation Administration has conducted wide-ranging tests over the past decade, and has reached a conclusion that potential flammability of magnesium is no longer deemed to be a concern.
[7] Modern surface treatment technologies provide protection from corrosion and significantly extend the average lifecycle of magnesium rims.
Wheels produced by this method can offer reductions in price and improvements in corrosion resistance, but they are less ductile and of lower strength due to the nature of high pressure die casting.
This process usually employs a steel die, it is arranged above the crucible filled with molten magnesium.
Gravity-cast magnesium wheels have been in production since the early 1920s and provide good ductility, and relative properties above what can be made with aluminium casting.
This has allowed small batch production, flexibility in design and short development time.
