What’s what with wheel fitments.
In the automotive wheel and tire industry, many wheels are categorized as either “hub-centric” or “lug-centric”. There are important differences between the two types of wheel fitments and what they are designed for, and we’re here to explain what’s what between the two and how they fit on a vehicle.
Hub-centric wheels are normally found on all factory-made vehicles. Automakers will design their OEM wheels to fit a specific vehicle or range of vehicles using a specific wheel bore size. This wheel bore is engineered to fit exactly onto the axle of a given vehicle, creating a hub-centric connection. A hub-centric connection is where the center of the wheel is connected directly to the axle hub. Lug nuts are used here to connect and secure the wheel to the mounting plate. In a hub-centric design, the wheel-to-axle connection actually bears the weight of the car as well as forces acting on the wheel upwards and downwards. Lug nuts are used to withstand the lateral forces while the car is in motion that push and pull the wheel to and away from the mounting plate.
A great deal of aftermarket wheel companies make wheels that have a center bore with a larger hub diameter in order to fit a wide range of vehicles. If the hub diameter is too small for a larger axle, it will not fit the given vehicle. So, aftermarket companies will often create large hub diameters to ensure that their wheels can be used for a larger variety of applications. Due to the larger size of the wheel’s hub diameter, there is empty space between the axle and the hub. This means that the wheel is centered by the lugs instead of the hub, making the fitment lug-centric.
Due to the fact that most aftermarket wheels have larger hub diameters, companies will offer small hub-centric rings as an option. These metal or plastic rings are made in a large range of sizes and can be installed inside the wheel hub so that the fitment is hub-centric instead of lug-centric.