Because they look cool right! The performance benefits of custom wheels should be your answer. In the 1950s and 1960s race car drivers developed lighter magnesium wheels to reduce weight and enhance performance in all form of racing. They were called Mags by the racers, a term still widely used today. However, most magnesium wheels were far too fragile for daily street use. Plus magnesium oxidizes very quickly and requires frequent polishing. Magnesium wheels used in modern race cars are often forged to make them stronger and reduce weight. As a result contemporary forged magnesium custom wheels are very expensive. The oxidization problem is the reason you don’t see contemporary custom wheels made of magnesium.
Fortunately for the custom wheel market today manufacturers developed light weight aluminum alloy wheels that provide the strength needed and come in numerous finish options while reducing wheel weight. Trendy wheel finishes include chrome and polished aluminum, plus painted aluminum alloy come in hyper-silver, silver, white, black, gray and Anthracite. While many of us choose aftermarket custom wheels for their good looks, there are many important performance benefits resulting from reducing a wheels weight compared to factory steel wheels.
The additional strength of a custom alloy wheels can notably reduce tire deflection and tire rollover while cornering. You also get increased brake cooling with custom alloy wheels because aluminum alloy is a great conductor of heat. The large mass of the aluminum wheels help dissipate heat from the brakes. The open design of 5 spoke and 6 spoke custom wheels allow more air flow over the brakes cooling them as you drive in city traffic.
One of the most significant factors affecting a car, truck or SUV road holding ability is the reduced weight of custom aluminum alloy wheels over factory steel wheels. By reducing weight, custom wheels provide improved acceleration and braking. You must also be careful not to exceed the design weight of the original wheels and have the reverse effect by adding larger wheels and tires or aluminum alloy wheels that are gravity cast. Gravity cast aluminum alloy custom wheels are cheaper but heavier and prone to bending. Look for aluminum wheels that are either low pressure cast or forged, they cost more but will reduced weight and add strength.