Researchers at IMDEA Networks Institute, together with European partners, have found that tire pressure sensors in modern cars can unintentionally expose drivers to tracking. Over a ten-week study, they collected signals from more than 20,000 vehicles, revealing a hidden privacy risk and highlighting the need for stronger security measures in future vehicle sensor systems.
Most modern cars are equipped with a Tire Pressure Monitoring System (TPMS), mandatory since the late 2000s in many countries for their contribution to road safety. This system uses small sensors in each wheel to monitor tire pressure and sends wireless signals to the car's computer to alert the driver if a tire is underinflated.
However, the researchers found that these tire sensors also send a unique ID number in clear, unencrypted wireless signals, meaning that anyone nearby with a simple radio receiver can capture the signal, and recognize the same car again later. Most vehicle tracking today uses cameras that need clear visibility and line-of-sight to a car. TPMS tracking is different: tire sensors automatically send radio signals that pass through walls and vehicles, allowing small hidden wireless receivers to capture them without being seen. Because each sensor broadcasts a fixed unique ID, the same car can be recognized repeatedly without reading a license plate. This makes TPMS-based tracking cheaper, harder to detect, and more difficult to avoid than camera-based surveillance, and therefore a stronger privacy threat.
To test how serious this risk is, the team built a network of low-cost radio receivers, located near roads and parking areas. The necessary equipment costs only $100 per receiver. In total, they collected more than six million tire sensor messages from over 20,000 cars.
"Our results show that these tire sensor signals can be used to follow vehicles and learn their movement patterns," says Domenico Giustiniano, Research Professor at IMDEA Networks Institute. "This means a network of inexpensive wireless receivers could quietly monitor the patterns of cars in real-world environments. Such information could reveal daily routines, such as work arrival times or travel habits."
The researchers also developed methods to match signals from the four tires of a car. This allowed them to increase the accuracy of specific vehicles arriving, living, or following regular schedules. The study showed that signals can be captured from moving cars and from distances greater than 50 meters, even when sensors are inside buildings or hidden locations. This makes covert tracking technically feasible.
Additionally, TPMS signals include tire pressure readings, which may reveal the type of vehicle or whether a car or truck is carrying heavy loads. This could allow more advanced forms of surveillance.
"As vehicles become increasingly connected, even safety-oriented sensors like TPMS should be designed with security in mind, since data that appears passive and harmless can become a powerful identifier when collected at scale," highlights Alessio Scalingi, former PhD student at IMDEA Networks and now Assistant Professor at UC3M, Madrid.
Despite these risks, current vehicle cybersecurity regulations do not yet specifically address TPMS security. The researchers warn that without encryption or authentication, tire sensors remain an easy target for passive surveillance.
"TPMS was designed for safety, not security," adds Dr. Yago Lizarribar, former PhD student at IMDEA Networks during the research study, and now Researcher at Armasuisse, Switzerland. "Our findings show the need for manufacturers and regulators to improve protection in future vehicle sensor systems."
Therefore, the research team urges the manufacturers and policymakers to strengthen cybersecurity in future cars, so that safety systems do not become tracking tools.
The paper, titled "Can't Hide Your Stride: Inferring Car Movement Patterns from Passive TPMS Measurements," has been accepted for publication at IEEE WONS 2026.
