TPMS: What is this new Tire Pressure Monitoring System all about?

There is a new Tire Pressure Monitoring System being mandated by the United States government that I thought you might want to know about. The TPMS started being installed on some 2000 models, and by September 1, 2007, all new vehicles will be equipped with a tire pressure monitoring system.

Studies have shown that about one out of every four vehicles on the road is running on under-inflated tires. This can lead to poor gas mileage and increased tire wear. Under-inflated tires can also cause accidents. Most tire failures are a consequence of tires slowly losing air pressure over a period of time. This causes the tire tread to wear unevenly and overheat, which can then cause premature and unexpected failure of the tire. On the other hand, over-inflation of one or more tires may also result in poor vehicle handling and reduced tire life.

The tire pressure monitoring system was created because not enough people check the air pressure of their tires, which have lead to accidents. There are two different systems that monitored the air pressure of tires.

In the interest of keeping costs low, the indirect tire pressure monitoring system was developed. It used the vehicle's antilock braking system's wheel speed sensors to compare the rotational speed of one tire vs. the others. Sorry to say, it has had shortcomings and is being phased out. Indirect systems don't tell the driver if all four tires are losing pressure at the same rate. We have found that vehicles with indirect systems generate a lot of false warnings. The warning light has come on when the vehicle is driven around a long curve that causes the outside tires to rotate faster than the inside tires, when driven on bumpy roads, or when the tires spin on ice and snow.

The direct tire pressure monitoring system is the system that will be installed in all newer vehicles. It offers accuracy and a quicker response compared to the indirect system. The disadvantage of the direct system is that it costs more to build, maintain and service.

Most direct tire pressure monitoring systems use special sensor/transmitters that are mounted in the tire valve stem. But this is no ordinary valve stem. It is a special metal clamp-in tire valve that is delicate and easily damaged. To power up the receiver a battery is installed in a sensor housing unit and attached to the valve stem. The battery will power the receiver for approx. 10 yrs.

It will cost you extra money to have tires changed that have a direct tire pressure monitoring system. If a shop tells you it won't, then I suggest you RUN away and have the work done somewhere else.

You will want to avoid shops that have a "race track pit-stop" approach to installing tires. They usually have several technicians working on the car at once. One takes the tires off the car, another pulls the rubber from the rim and glues the new tire on, and then passes them back to be put on the car. Because the valve stem is so delicate, speed is the last thing you want.

Special training is required to prepare for the changes that the tire pressure monitoring system demands. Technicians need a sound understanding of how to identify a vehicle with a TPMS, how to service and install the valve stem sensor, and how to protect the sensor during the demount/mount process. They will also need to invest in special sensor monitoring/recalibrating tools and advanced balancing equipment.

Each time a tire is remounted that has a tire pressure monitoring system a new set of seals will need to be installed. This will cost approx. $8.00 per tire. The sensor also needs to be reprogrammed to bring the system back online. To change a tire with a direct TPMS, a slow and deliberate approach is demanded. Delicate and easily broken, each replacement stem/battery can cost up to $300.00 to replace. OUCH!

If your vehicle doesn't have TPMS, you should check your tire inflation pressure (including the spare) at least once a month and before every long trip.

The correct air pressure for your tires can be found on the tire information sticker on the vehicle's door edge, door post, glove box door or fuel door. Don't use the pressure rating stamped on the side of the tire. This is not the correct pressure rating for you car, it is the maximum allowed for that tire. But, you will find the proper air pressure for your donut- spare tire on its sidewall.

It is best to check the tire pressure when the tires are cold or before the vehicle has been driven more than two miles. As the vehicle is driven, the tires heat up and the tire pressure rises and you will get an incorrect reading.

If you become your own TPMS you will be able to identify potential problems before they happen. You can avoid a flat tire or even worse an accident in the car that can damage you, loved ones or your vehicle.

The TPMS really complicates the tire changing process. The consumer is loosing more control over doing-it-yourself with changing their tires. By law, we can not mount regular rims / regular tire valves on a vehicle that came with original TPMS. and I'm sure if someone got into an accident with regular rims/regular tire valves on a vehicle that came with original TPMS, they would get sued and lose.

Happy Motoring,

Amy