What Is a Lug Wrench? Definition, Meaning and Concept

Conveniently, a lug wrench is a tool designed to loosen and tighten nuts. The nuts are responsible for keeping the tires attached to the axles, which means that they are usually kept very tight. Professional mechanics typically use pneumatic sockets to accomplish this feat, ensuring the lug nuts won't come loose during normal driving. A lug wrench is designed to provide drivers with enough leverage to loosen lug nuts during a roadside emergency.

There are two common lug wrench designs that drivers may encounter. One is a metal bar bent at the end closest to a socket wrench. The other common socket wrench configuration resembles a cross, with multiple sockets on each arm.

Both provide enough leverage for a driver to loosen lug nuts, but many experts recommend the cross-shaped lug wrench for maximum leverage. However, the bent arm lug wrench features a pry bar on the opposite end, which can make removing hub caps or other wheel covers much easier. Any type of lug wrench can be purchased at an auto supply store or department store.

The lug wrench comes into play most often with a flat tire. The driver usually removes the spare tire, car jack, and lug wrench from the trunk to replace the tire. Once the hubcap or wheel cover is removed, the lug nuts are revealed.

The driver must loosen, but not remove, all lug nuts before jacking up the car. This involves placing the lug wrench over a nut and applying downward force until the nut loosens. Once the nut is loose enough to turn by hand, the driver repeats the process with the rest of the nuts. Using a cross-shaped lug wrench, the driver should be able to apply both up and down pressure on the left and right arms. This extra torque is why many professionals prefer the cross-shaped wrench.

Great care must be taken not to remove the socket from a lug wrench. If the end of a bent arm lug wrench is not properly attached to the nut, excessive force can damage the nut or socket. A lug wrench made from softer metals may be less expensive than a forged steel model, but may not be able to handle the tougher nuts. It's not uncommon for car owners to replace the factory supplied lug wrench and car jack with higher quality tools from an auto supply store.