Tire Pressure Monitoring System(TPMS): Everything You Need to Know

Oct. 30, 2024

What Does TPMS Mean?

TPMS stands for Tire Pressure Monitoring System. This system uses electronic sensors installed in the tires to automatically monitor various tire conditions in real-time, including pressure, temperature, and battery status. By recording tire speed and other data, TPMS provides essential safety and effectiveness for vehicle operation.

The TPMS (Tire Pressure Monitoring System) Scan Tool is a diagnostic device for reading and diagnosing faults in a vehicle's tire pressure monitoring system. It can be used to check tire pressure sensors, monitor tire pressure, and reset the TPMS warning light on the instrument cluster.

Types of TPMS

Tire pressure monitoring systems can be classified into two categories: direct TPMS and indirect TPMS.

Direct TPMS: This system utilizes pressure sensors installed inside each tire to measure air pressure and temperature. The sensors then transmit the data to the vehicle's onboard computer via a wireless transmitter. When tire pressure is too high, too low, or the temperature is excessive, the system alerts the driver. Additionally, the warning thresholds for tire pressure and temperature can be customized by the vehicle owner based on the vehicle model, driving habits, and geographical location. Direct TPMS offers accurate, real-time tire pressure data, making it a more reliable option. A direct TPMS setup uses sensors placed inside each tire to measure their individual pressure. Such systems are usually accurate to within 1 psi. Current direct systems use a sensor mounted to the wheel or tire valve, which sends a signal to the car's computer. How the data is interpreted and displayed in the car with a direct TPMS depends on whether it is a low-line or high-line unit.

Indirect TPMS: This system calculates tire pressure indirectly using wheel speed sensors and data from the vehicle's antilock braking system (ABS). Indirect TPMS does not require individual pressure sensors in each tire, making it a more cost-effective solution. However, it may not provide as precise data as direct TPMS and could struggle to detect gradual tire pressure loss.

How Do Indirect and Direct TPMS Work?

Indirect Tire Pressure Monitoring System (TPMS)

The indirect TPMS detects changes in tire pressure by monitoring wheel speed. When a tire’s pressure decreases, its diameter reduces, causing it to rotate faster than the other tires. Wheel speed sensors pick up this increase in rotation speed and send signals to the vehicle's Electronic Control Module (ECM). The ECM analyzes these signals to identify the tire with low pressure; if one tire is spinning significantly faster than the others, it concludes that this tire is underinflated and sends a warning signal to alert the driver.

Direct Tire Pressure Monitoring System (TPMS)

In contrast, the direct TPMS measures tire pressure through sensors installed within each tire. These sensors transmit real-time data to the central control module, which compares the actual tire pressure readings with preset values. If it detects that tire pressure is either too high or too low, the system alerts the driver through a warning light on the dashboard or a notification on the vehicle’s display. This direct TPMS offers continuous monitoring, enabling drivers to take timely action to prevent tire damage.

· High-line TPMS systems have sensors mounted in each wheel well, allowing the instrument cluster to display the pressure for each individual tire.

· Low-line systems, typically found in less expensive vehicles, only illuminate a low-pressure warning light. Drivers must then determine which tire is underinflated, similar to indirect TPMS systems.

To determine whether a vehicle—especially a used one—has a direct or indirect TPMS system, you usually need to inspect the tires. As a rule of thumb, most vehicles from the 2008 model year onward are equipped with direct TPMS.

If you prefer a high-line system, check the instrument cluster during a test drive. Navigate the menus, and if individual tire pressures are displayed, the car has a high-line system. If not, keep a reliable tire pressure gauge in your glovebox to manually monitor tire pressures—it’s an inexpensive and essential tool for vehicle safety.

Tire Pressure Monitoring System: Advantages and Disadvantages

The tire pressure monitoring system (TPMS) is a technology designed to monitor tire pressure, offering several benefits and drawbacks.

Advantages

1. Extended Tire Life: Proper tire inflation is crucial for preventing uneven tire wear. A TPMS helps ensure tires are correctly inflated, thereby extending their lifespan and reducing the risk of premature failure, which can lead to costly repairs.

2. Improved Fuel Efficiency: When tires are inflated to the recommended pressure, fuel efficiency increases. Underinflated tires create higher rolling resistance, resulting in decreased fuel economy.

3. Reduced Environmental Impact: Correctly inflated tires contribute to lower fuel consumption, which in turn helps minimize greenhouse gas emissions from vehicles.

4. Enhanced Safety: By continuously monitoring tire pressure, a TPMS alerts drivers to potential issues, allowing for timely corrective actions. This proactive approach can prevent tire blowouts and improve overall road safety.

Disadvantages

1. Costly Installation: Installing a TPMS can be expensive. Furthermore, the system requires regular maintenance to ensure proper functionality, which may involve replacing batteries, sensors, or other components.

2. False Alerts: TPMS can issue false alarms if sensors are damaged or malfunctioning, leading to driver frustration and the potential to overlook genuine warnings.

3. Limited Monitoring Range: TPMS sensors have a restricted range, which may prevent accurate monitoring of tire pressure on vehicles that are towing trailers or traveling long distances.

Direct TPMS : Advantages & Disadvantages

The primary purpose of a TPMS (Tire Pressure Monitoring System) is to alert drivers when tire pressure drops below safe levels. Under-inflated tires can compromise driving safety and cause vehicle damage or serious injury. TPMS notifies you immediately so corrective action can be taken before problems escalate.

Direct TPMS systems use pressure sensors inside each tire to continuously monitor air pressure. Some sensors also provide temperature readings. The data is transmitted wirelessly to a central control module, which processes it and sends alerts to the dashboard if tire pressure falls below the recommended level.