Purcellville Tire & Auto
720 East Main Street, Purcellville, VA 20132 540.338.6667

Tire Pressure Monitoring System


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All new cars and light trucks in Purcellville VA since 2008 have come equipped with a tire pressure monitoring system, or 'TPMS'. The TPMS system detects when a tire becomes under-inflated and lights up a warning light on the dash.

So what's the big deal? Well, under-inflated tires can be a real safety concern for everyone in VA. First of all, they don't handle properly and that can lead to an accident. Second, under-inflated tires can overheat and cause the tire to come apart, which can also lead to an accident.

Government regulations requiring TPMS systems aim to reduce accidents in VA and save lives: A very worthy goal. There are also positive environmental effects because under-inflated tires are fuel wasters – you lose 1 percent of your fuel economy for every 3 pounds of pressure below ideal. So proper tire inflation can save you a tank of gas a year. And your tires last longer so you won't have to replace them as often.

There are two kinds of TPMS systems. So-called direct systems have a battery powered sensor in each wheel that measures tire pressure. The sensor sends a signal to a receiver that illuminates the warning light if pressure is low on a tire.

Indirect systems use a computer program to detect under-inflation by measuring wheel rotation speeds and other data.

You'll have to replace TPMS parts as they wear out. Obviously, the batteries in the sensors will run out someday. Road salt and grime can damage sensors too. The system needs to be reset when you rotate or change your tires.

Because the TPMS system is so important to your safety, you should make the necessary repairs when needed. And remember, TPMS is no substitute for regularly checking your tire pressure– at least once a month.

Your Tire Pressure Monitoring System warning light goes off when a tire is 25 percent under inflated. If your recommended pressure is 32 psi, 25 percent below means you are at 24 psi; which is severely under inflated. At that low pressure, your safety is at risk, your fuel economy is hurt, and your tire is wearing out too fast. Check your pressure at least once a month. At Purcellville Tire & Auto in Purcellville we install quality NAPA replacement parts. Give us a call at 540.338.6667 and let us help keep you safely and economically on the road.