What are Tire Pressure Monitoring Systems (TPMS)?
Tire Pressure Monitoring Systems (TPMS)
The TPMS’ purpose is to alert drivers that one or more tires on the vehicle are under-inflated and unsafe to drive on. TPMS were first introduced in the 1980’s in the European market and in the early 1990’s in the United States. The Transportation Recall Enhancement, Accountability, and Documentation (TREAD) Act was later implemented for automakers to put the TPMS technology in motor vehicles under 10,000 lbs. to indicate under-inflated tires. In the late 2000’s and early 2010’s, U.S and European lawmakers enacted that most motor vehicles must be supplied with TPMS technology.
How the Tire Pressure Monitoring System Work
When one or more tires are under-inflated or compromised, a sensor in the tire sends a signal to the dashboard. The light on the dashboard can be described as an exclamation mark within a horseshoe-like symbol. This indicator can either represent an indirect or direct TPMS.
Indirect TPMS (iTPMS)
Indirect TPMS (iTPMS) measures air pressure using software-based systems that evaluate and combine sensor signals such as wheel speeds, accelerometers (measures acceleration), and driveline data to observe the tire pressure. With this system, there are some pros and cons:
- Less expensive than a direct TPMS
- Less programming and upkeep over time
- Less installation maintenance
- Inconsistent if a smaller or bigger tire is purchased
- Unreliable if tires have uneven wear and tear
- Must be reset after inflating tire(s) or tire rotation services
Direct TPMS (dTPMS)
Direct TPMS (dTPMS) measures tire pressure using hardware sensors. Each wheel has a pressure sensor which transmits the information to a central control unit and then to the vehicle’s onboard computer.
- Direct tire pressure reading from inside the tire
- More accurate readings than indirect TPMS
- Battery-powered sensors with tire last a decade
- Does not have to reset after tire maintenance services
- More expensive than indirect TPMS
- Resyncing system can be costly
- If battery drains, would need to be replaced
- Sensors can be damaged easily during maintenance
- Servicing can be nuisance for auto shops due to proprietary systems
Benefits of a TPMS in Fleet
While there are variations with each TPMS, both serve the same purpose to ensure the safety of the driver. The benefits of having a TPMS present can reduce accidents, extend tire life, reduce emissions, and improve vehicle mileage.