Tire Pressure Monitoring Systems

Have you ever driven your car on the freeway only to find later that one of the tires was dangerously low on air? With most modern tires it is very hard to tell if a tire is low by looking at the tire. With run-flat tires, it is impossible to tell by looking because the sidewalls are designed to hold the weight of the vehicle if the tire loses air. A tire pressure monitoring system (TPMS) would warn you about the low inflation pressure before you took to the road, giving you the chance to correct the situation before it becomes a problem.

There are currently two types of tire pressure monitoring systems available for passenger cars and light trucks.

Direct tire pressure monitoring system – These systems use a special air valve that contains a tiny radio transmitter. The transmitter sends a signal to a receiver in the car that illuminates a warning light on the dash, letting the driver know he has a low tire. So far, these have proven to be the most reliable system of the two. The batteries that are built into the transmitters have a life of 7-10 years, so frequent replacement isn't an issue. A direct tire pressure monitoring system can be installed easily on any car.

Indirect tire pressure monitoring system – Instead of measuring the tire pressure directly, this system utilizes the anti-lock brake sensors to detect the rotational speed of the tires. A tire that is low on air would turn at a slightly faster speed. When this different speed is detected, that information is sent to the vehicle's computer and a warning light on the dash is illuminated to let the driver know of the low tire.

Indirect systems have a couple shortcomings – if a car is driven in slippery conditions it may report a tire that is spinning as being low on air pressure when it isn't. Another shortcoming is if all tires are low on air by the same amount, the computer will not see this as a problem and will not illuminate the low tire pressure warning light on the dash. This gives a slight edge to direct tire pressure monitoring systems, which read the actual pressure in the tire.

Adding a tire pressure monitoring system
Tire pressure monitoring systems will soon be mandatory on all passenger cars and light trucks in the USA. They have been available on new cars for the past couple years.

If your car doesn't have one already, a direct tire pressure monitoring system can be added to any vehicle. They are readily available as an aftermarket accessory.

To install the system, you may need to take your car to the nearest tire store and have them change the tire valves and stems to the new ones that are included in the kit. Install the receiver and display in the car where it can be seen by the driver, program the receiver per the instructions included with the kit, and you're ready to go.