recognize the sensor positions and must ignore the signals from other vehicles. Aftermarket dTPMS units not only transmit while vehicles are moving or parked, but also provide users with some advanced monitoring options including data logging, remote monitoring options and more. They are available for all types of vehicles, from motorcycles to heavy equipment, and can monitor up to 64 tires at a time, which is important for commercial vehicles. Many aftermarket dTPMS units do not require specialized tools to program or reset, making them much simpler to use. Maintenance issues Valve-stem corrosion First-generation of TPMS sensors that are integral with the valve stem have suffered from corrosion. Metallic valve caps can become seized to the valve stem because of galvanic corrosion of dissimilar metals, and efforts to remove it can break the stem, destroying the sensor. A similar fate may befall an after-market brass valve core inside the stem that may have been installed by unwary technician, replacing the original specialized nickel-coated cores. (They can be distinguished by the yellowish colour of the brass.) Seizure of the valve can complicate repair of a tire leak, possibly requiring replacement of the entire sensor. Tire sealant compatibility There is controversy regarding the compatibility of after-market tire sealants with dTPMS that employ sensors mounted inside the tire. Some manufacturers of sealants assert that their products are indeed compatible, but others warned that the "sealant may come in contact with the sensor in a way that renders the sensor temporarily inoperable until it is properly cleaned, inspected and re-installed by a tire care professional". Such doubts are also reported by others. Use of such sealants may void the TPMS sensor warranty. Benefits of TPMS The dynamic behavior of a pneumatic tire is closely connected to its inflation pressure. Key factors like braking distance and lateral stability require the inflation pressures to be adjusted and kept as specified by the vehicle manufacturer. Extreme under-inflation can even lead to thermal and mechanical overload caused by overheating and subsequent, sudden destruction of the tire itself. Additionally, fuel efficiency and tire wear are severely affected by under-inflation. Tires do not only leak air if punctured, they also leak air naturally, and over a year, even a typical new, properly mounted tire can lose from 20 to 60 kPa (3 to 9 psi), roughly 10% or even more of its initial pressure. The significant advantages of TPMS are