Loose wheel nut indicators are small pointed tags, usually made of fluorescent yellow plastic, which are fixed to the lug nut

Lug nut

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 , and other large vehicles utilizing rubber tires.-Design:...

s of the wheels of large vehicles. The tag rotates with the nut, and if the nut becomes loose, the point of the tag shifts noticeably out of alignment with the other tags. If too many lug nuts are loosened, the wheel can detach from the wheel stud

Wheel stud

Wheel studs are the threaded fasteners that hold on the wheels of many automobiles. They are semi-permanently mounted directly to the vehicle hub, usually through the brake drum or brake disk. Lug nuts are fastened over to the wheel stud to secure the wheel...

; loose wheel nut indicators allow identification of loose nuts before this can occur.

Loose wheel nut indicators are used both by auto mechanic

Auto mechanic

An auto mechanic is a mechanic with a variety of car makes or either in a specific area or in a specific make of car. In repairing cars, their main role is to diagnose the problem accurately and quickly...

s to identify lug nuts which require tightening, and by accident investigators

Accident Analysis

Accident analysis is carried out in order to determine the cause or causes of an accident or series of accidents so as to prevent further incidents of a similar kind. It is also known as accident investigation. It may be performed by a range of experts, including forensic scientists, forensic...

 to detect faults after accidents. Although not compulsory in most jurisdictions, road safety bodies recommend their use, especially on large or heavy vehicles such as bus

Bus

A bus is a road vehicle designed to carry passengers. Buses can have a capacity as high as 300 passengers. The most common type of bus is the single-decker bus, with larger loads carried by double-decker buses and articulated buses, and smaller loads carried by midibuses and minibuses; coaches are...

es, coach

Coach (vehicle)

A coach is a large motor vehicle, a type of bus, used for conveying passengers on excursions and on longer distance express coach scheduled transport between cities - or even between countries...

es, and truck

Truck

A truck or lorry is a motor vehicle designed to transport cargo. Trucks vary greatly in size, power, and configuration, with the smallest being mechanically similar to an automobile...

s.