lug nut

Lug-nuts on an Acura.

A lug nut is a fastener, specifically a nut, used to secure a wheel on a vehicle. Typically, lug nuts are found on automobiles, trucks (lorries), and other large vehicles utilizing rubber tires.

Design

A lug nut can be described as being a nut with one rounded or conical (tapered) end, used on steel and most aluminum style wheels. A set of lug nuts are typically used to secure a wheel to threaded wheel studs and thereby to a vehicle's axles. Some designs use lug bolts instead of nuts, which screw into a tapped (threaded) hole. This configuration is commonly known as a bolted joint. The lug's taper is normally 60 degrees (although 45 is common for wheels designed for racing applications), and is designed to center the wheel accurately on the axle, and to reduce the tendency for the nut to loosen, due to fretting induced precession, as the car is driven. Honda uses a spherical rather than a tapered seat, but the nut performs the same function. Older style mag wheels have a 1/2 to 1 inch shank slipping into the wheel to center it and a washer that applies pressure to clamp the wheel to the axle.

Removing and replacing

Only one basic tool is needed to remove/replace lug nuts, usually a lug wrench. If the wheel is to be removed then an automotive jack and some wheel chocks to raise the vehicle would be used as well. Wheels that have hubcaps or hub covers a need these removed beforehand, typically with a screwdriver^[1].

History

Some cars made up to about 1960 used left-hand and right-hand threaded lug nuts for different sides of the vehicle to prevent loosening, until it was realised that the taper seat performed the same function. In order to allow the easy detection of loose lug nuts, some large vehicles are fitted with loose wheel nut indicators, which spin with the nut and highlight misaligned nuts.

See also

• Center cap

References