Wheel lug nuts are the only things holding your vehicle's wheels to the hub. They use a specific thread pitch to screw onto the hub's wheel studs. Unlike standard hardware store nuts, lug nuts feature a tapered (conical, spherical, or flat-seated) shoulder. This tapered seat aligns the wheel perfectly center on the hub and prevents the nut from loosening due to wheel vibrations.
Always tighten lug nuts in a star pattern using a torque wrench set to the manufacturer's specifications. Tightening them out of order or using an impact gun without a torque stick can warp the brake rotors and stretch the studs. Worn, rusted, or cross-threaded lug nuts should be replaced immediately. Never apply grease or anti-seize to the studs unless specifically instructed, as this changes the torque readings.