75% of flat tires are caused by under-inflation or slow leakage and tire problems are the third most common reason for passenger vehicle breakdowns. Fuel consumption increases 1.5% and the life span of a tire decreases 15% with every 0.2 bar the tire is under-inflated. Approximately 20% of all passenger cars have tires which are under-inflated by up to 40%. NIRA Dynamics has the solution to these problems: An indirect tire pressure monitoring system called TPI - Tire Pressure Indicator.

With TPI, the driver will be alerted if any of the tires is under-inflated long before the tire breaks down. This improves safety. It also improves economy and decreases the environmental impact since tire wear and fuel consumption are reduced when tires are correctly inflated.

TPI is a software solution which determines the tire inflation pressure from the wheel speed signals and does not require any extra sensors. TPI is therefore very cost effective and easy to integrate into different target systems. The system currently supports the following vehicle configurations

• Front wheel driven (FWD)
• Rear wheel driven (RWD)
• All wheel driven (AWD) with a fixed slip-distribution (using e.g. a Torsen-like differential)
• All wheel driven (AWD) with a known torque distribution

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.

TPI is delivered as a software component with standardized software interfaces (APIs). TPI can be delivered in different configurations. TPI is part of the ND4 Suite, which is a package of safety enhancement functions for passenger cars, light trucks and SUVs. The ND4 Suite also includes RFI (Road Friction Indicator) and HPY (High Precision Yaw rate).