Tire pressure is important. How important? Without tires, what would your vehicle ride on? What would control the car? If your tires are not properly inflated, the handling characteristics of the car change drastically. Optimal inflation will bring better performance and fuel economy; thus, it is important enough to have its own warning system: TPMS (Tire Pressure Monitoring System).
We’ve all seen it; maybe it’s the exclamation point that makes it so apparent. As a requirement for any car purchased after September 2007, the TPMS warning light is one of the most recognizable symbols for drivers. It’s an aid to let us know that the inflation is not correct on the only contact points (and thus one of the most important parts) of our cars. , which could lead to much more severe issues.
Each car manufacturer has different levels of systems, but they all ultimately accomplish the same result: warning you that the tire pressure is out of a specified/recommended range. BMW’s TPMS system is on the more advanced side, utilizing progressive sensors that not only give the PSI of each tire, but the temperature as well.
This is great for those that track cars or prefer to monitor tire temp along with pressure. This can also be an issue if you have multiple wheel sets or tend to swap wheels often, you’ll have to buy an additional sensor for each wheel you purchase.
At around $60 per sensor minimum, it can get rather expensive quickly. I've had excellent results from the CUB TPMS sensors, which I opted for on my daily driver ///M3.
Audi’s system is considered a “passive” TPMS system, as it does not require individual sensors installed onto each rim like BMW. It's more along the lines of other manufacturers, which simply warn when air pressure reads beyond the set range, but it can do so by individual tire.
A nice advantage to this system is that you do not need to swap sensors or purchase additional sensors when you change out your wheels (great for those of us aftermarket guys!); it’s simply plug and play, as Audi sensors are within the wheel hub on each corner and measure inflation via a combination of the wheel speed sensors and the electronic stability control. Once you've set your preferred pressure, you just have to store the current configuration in the system.
Not only specific to road cars, TPMS has made its way to off-road vehicles and light trucks as well. While the daily advantages are the same as normal cars, once off-road, TPMS can become somewhat of a nuisance.
Traditionally, 4x4 enthusiasts like to air down their tires when hitting the trails. Although not necessary, you can expect a smoother off-road ride and better traction, mostly on rocks, sand and snow. However, this causes your TPMS to alert you about the change in pressure.
This can be reset of course, but even after reconfiguring the TPMS, you’ll have to go through the trouble of having some sort of portable air compressor or storage tank. In addition, you will lose ground clearance and run the risk of damaging your tires and rims.
Whether it’s on-road or off-road, TPMS is great tool to have for both safety and performance; just keep in mind, as with any warning, it only truly works if you pay attention to it.