NIRA Dynamics’s TPI (Tire Pressure Indicator) is a software solution that determines the tire inflation pressure from the wheel speed signals and does not require any in-wheel pressure sensors and RF components. As a result, TPI is a cost effective and easy to integrate into different target systems. With TPI, the driver will be alerted if any of the tires is under-inflated long before the tire breaks down.
The indirect TPMS uses wheel vibration resonance measurement to estimate tire pressure from an anti-lock brake or traction control system. It can detect deflation on each wheel separately and is active after just 5 minutes of calibration. Enhanced indirect TPMS has the potential to satisfy Standard 138 of the FMVSS (Federal Motor Vehicle Safety Standards) and the TREAD (Transportation Recall Enhancement, Accountability and Documentation) requirements. With the new indirect system, OEMs can install the same, low-cost TPMS system on all models, whether or not they will be sold in the US market, without installing the complicated and costly pressure sensors on each tire and RF (radio frequency) modules, as used in direct measuring systems.
The performance of TPI is comparable to a direct sensor-based system, but at a significantly lower total cost. TPI is capable of detecting pressure drops in one, two, three, or even up to all four tires. After detection of a low pressure condition, the system can point out (isolate) in which tire or tires (up to all four) that are under-inflated. The system is very robust against surface changes, load variations and driving styles. Also, TPI automatically adjusts to different types of tires: summer tires, studded winter tires, run-flat tires etc.
More info: NIRA Dynamics Tire Pressure Indicator (pdf)