FAT3 Glossary

A federal agency that regulates transportation safety in the United States, including vehicles’ wheels and tires. The DOT requires a code—a series of letters and numbers—to be stamped into the sidewall of every tire made for public use in the United States. These codes contain information such as the date of manufacture and the plant where the tire was manufactured.

A leak detection device that uses a sensitive microphone to hear small refrigerant leaks by amplifying the hissing noise.

Seals that surround the top of the valve stem to prevent excessive oil from leaking into the valve guide.

A condition in which the vehicle’s front wheels are turned more sharply than the vehicle’s actual direction because the front tires lose adhesion during cornering. The vehicle is said to be pushing in the corners.

A vehicle design that does not use a rigid frame to support the body. The body panels are designed to provide the strength for the vehicle.

Used in the standard bolt system. A bolt with fewer threads per inch for a given diameter.

Used in the standard bolt system. A bolt with more threads per inch for a given diameter.

The distance from the center of one coil to the center of the adjacent coil in a spring is the same distance throughout the length of the spring.

A standardized grading system, established by the National Highway Traffic Safety Administration, designed to provide tire buyers with a comparative measure of a tire’s tread life, traction, and temperature characteristics.

The process of matching the tire’s highest point with the wheel’s lowest point, which may or may not be at the valve stem, for the purpose of reducing the tire’s radial imbalance.