What is Tire-pressure gauge?

A tire pressure gauge referred to as a tire pressure gauge, is a pressure gauge used to measure vehicle tire pressure.The recommended tire pressure for most passenger vehicles is 32 to 35 pounds per square inch when they are not warmed up from driving.Since tires are rated for specific loads at specific pressures,it is important to maintain tire pressures at optimum values.Tires are rated for optimum pressure when they are cold, which means this will eventually change the internal pressure of the tire due to gas expansion before the tire has been driven for a day and allowed to heat up.As shown, a typical mechanical pressure gauge has an accuracy of ±3 psi (21 kPa).Higher accuracy gauges with an uncertainty of ±1 psi (6.9 kPa) are also available.

Tire pressure monitoring system

Many modern cars are now equipped with built-in tire pressure sensors that can read all four tire pressures simultaneously from inside the car.Before 2005, most on-board tire pressure monitoring systems (TPMS) used indirect pressure monitoring.Antilock brake sensors detect that one tire is spinning faster than the others and indicate to the driver that tire pressure is low.The problem with this approach is that if the tires all lose the same pressure then none of the tires will have a problem with the others.However, studies have shown that direct and indirect tire pressure monitoring systems are equally effective.

Regulations on tire pressure 

Beginning September 2007,all new vehicles sold in the under 10,000 lbs (4,500 kg) must be equipped with a tire pressure monitoring system capable of monitoring all four tires and simultaneously reporting cold signs that are 25 percent under-inflated All Pressures for any combination of four tires.The TPMS is called Direct TPMS and is capable of simultaneously measuring the pressure of each tire pressure in compliance with the TREAD Act regulations.