Are Wheel Adapters Safe?

Wheel adapters are used to put a wheel on a vehicle that would not normally fit. They are typically made of aluminum or steel and are available in a large array of sizes and types to fit most wheels to most automobiles. As long as the change is not drastic and weight and size limits are observed, wheel adapters can be safely used.

The first widespread use of wheel adapters began with the Volkswagen Beetle. The original Volkswagen Beetle had a very wide bolt pattern that made it virtually impossible to make decorative rims for. People began making adapters to adapt readily available Chevrolet and Ford aftermarket rims to the Volkswagen Beetle, and the wheel adapter was born. Today, wheel adapters are available for a variety of applications.

The most common type of wheel adapter is a heavy, flat disk of metal, usually made from aluminum or steel, with holes and wheel mounting studs pre-drilled and installed. Some are designed to allow mounting of metric bolt pattern wheels to SAE pattern vehicles or vice-versa. These wheel adapters may also be used when a drastic change is required, such as when mounting SAE wheels on an older bolt-pattern Volkswagen Beetle. Some wheel adapters are used solely to increase spacing between the tire and the hub so that a wider-than-normal tire can be used.

The purpose of a wheel adapter is to allow a wheel to be placed on a vehicle upon which it would not normally fit. Wheel adapters have two bolt patterns to accomplish this task. The first pattern is the holes, which match the vehicle's hub. The second pattern is the bolts, which protrude from the adapter and mate to the new wheel. Wheel adapters can be safely used to space wheels away from a vehicle on which the pattern matches the wheel, but insufficient space exists to mount the wheel. The adapter is bolted to the vehicle first, with special countersunk lug nuts. The wheel is then bolted to the adapter as if it were the original hub.

Wheel adapters always change wheel geometry. Due to the way in which they are installed, they cause the vehicles footprint, or stance, to become wider. This changes the alignment geometry and front-wheel alignment must be performed to ensure proper steering and cornering. Front-wheel-drive cars require the rear alignment to be corrected as well. Wheel adapters should not be used in load hauling situations, such as on pickup trucks. The added distance between the wheel and the wheel bearing creates leverage that did not exist previously, which increases the chance of failure under load.

Wheel adapters are designed primarily for decorative retrofitting of aftermarket wheels. They are not designed for heavy hauling or hard cornering, and low-quality wheel adapters may fail under these conditions. "Uni-lug" wheel adapters should be avoided. These adapters are meant to fit a variety of cars and adapt them to a common pattern. Uni-lug wheel adapters have slots rather than holes and may become misaligned by road debris, potholes, or other road hazards. If this misalignment occurs at highway speeds, the wheel adapter may fail and cause an accident.