Tire-pressure gauge

A tire-pressure gauge, or tyre-pressure gauge, is a pressure gauge used to measure the pressure of tires on a vehicle. Proper tire pressure is crucial for vehicle safety, fuel efficiency, and tire longevity. Tire gauges come in various types, including analog, digital, and dial gauges, each offering different features and accuracy levels. Tire-pressure gauges can be used both professionally and casually and come in many different sizes.

A tire-pressure gauge displaying bar (outside) and psi (inside)

Since tires are rated for specific loads at certain pressure, it is important to keep the pressure of the tire at the optimal amount. The precision of a typical mechanical gauge as shown is ±3 psi (21 kPa). Higher precision gauges with ±1 psi (6.9 kPa) uncertainty can also be obtained.

Tire-pressure monitoring systems

Main article: Tire-pressure monitoring system

Many modern cars now come with built-in tire pressure sensors that allow all four tire pressures to be read simultaneously from inside the car. Before 2005, most on-board tire-pressure monitoring systems (TPMS) used indirect pressure monitoring. The anti-lock brake sensors detect one tire rotating faster than the rest and indicate a low tire pressure to the driver. The problem with this method was that if tires all lost the same pressure then none would show up against the others to indicate a problem. However, research have shown that both direct and indirect tire pressure monitoring systems are equally effective.

Types of tire-pressure gauges

Analog Gauges

• Dial Gauges feature a round dial with a needle that moves to indicate the tire pressure. The pressure is usually displayed in pounds per square inch (PSI), bar, or kilopascals (kPa). Dial gauges are known for their durability and ease of use.
• Pen-Type Gauges are compact gauges that resemble a pen and have a small dial or scale for reading pressure. They are portable and often used for their simplicity and convenience.

Digital Gauges

• Electronic Gauges use electronic sensors to provide a digital reading of tire pressure. They often come with backlit screens for better visibility and may include additional features such as memory functions for storing previous readings or automatic shutoff to conserve battery life.
• Smart Gauges are equipped with Bluetooth technology to sync with smartphones, allowing users to monitor tire pressure through a mobile app. These smart gauges can provide real-time data and alerts.

Beam Gauges

• Beam gauges use a mechanical lever and a scale to measure tire pressure. They are less common but offer a straightforward, no-frills approach to pressure measurement. Their accuracy depends on the quality of construction.

Regulations on tire pressure

Since September 2007 all new automobiles below 10,000 lb (4,500 kg) in weight sold in the United States are required to incorporate a Tire Pressure Monitoring System, which is capable of monitoring all four tires and simultaneously reporting under-inflation of 25 percent of cold placard pressures in any combination of all four tires. TPMS known as Direct TPMS are capable of TREAD Act legislation requiring simultaneous pressure measurement for each tire pressure.