Wheel nuts (or lug nuts) are the heavy-duty hexagonal nuts used to secure the wheel to the vehicle’s hub. They are used on vehicles that have threaded studs sticking out of the wheel hub. The “seat” of the nut—the end that touches the wheel—is critical; it is usually tapered (conical) or rounded (ball seat) to center the wheel perfectly. Using the wrong type of nut or overtightening them can damage the wheel rim or cause the wheel to wobble while driving.