Tire Pressure Monitoring System (TPMS) has two main types based on how it works: direct and indirect TPMS. Of course, direct vs indirect TPMS has its own comparisons and differences.
The obvious difference between direct vs indirect TPMS in how it works is that direct TPMS sends real-time sensor data, while indirect TPMS is calculated by using the ABS (Anti-lock Braking System) and ESP (Electronic Stability Program) first.
This article will inform you about direct vs indirect TPMS, from the difference in how it works to the comparison between the two.
How Direct vs Indirect TPMS Works
There are two main types of Tire Pressure Monitoring System based on how it works:
Direct TPMS
Direct TPMS uses pressure sensors mounted on each tire to measure air pressure directly. It sends pressure and temperature data to the control unit in the vehicle. If there is a significant change, the system will give a warning.
Indirect TPMS
Indirect TPMS does not measure air pressure directly. Instead, it uses wheel speed sensors integrated with the vehicle’s ABS to monitor the difference in rotation speed between the tires.
If one tire rotates faster than the other, this could be an indication of low pressure, and the system will give a warning.
The Differences of Direct vs Indirect TPMS
In general, the difference between the two types of TPMS is that direct TPMS obtains pressure data directly from the tires, while indirect TPMS estimates tire pressure. Here are the differences between direct vs indirect TPMS:
| Comparison | Direct TPMS | Indirect TPMS |
| How it works | Pressure sensors in each tire monitor pressure levels | Wheel speed sensors measure how fast tires are rotating |
| Accuracy | More accurate, usually within 1 psi | Less accurate, may not detect pressure loss in all conditions |
| Maintenance | Susceptible to damage during mounting/demounting | Requires less programming and maintenance |
| Cost | May be more expensive than indirect TPMS | May be less expensive than direct TPMS |
Direct or Indirect TPMS: Which Does Your Car Have?
The choice of TPMS type is determined by the manufacturer. Typically, the system is tailored to the vehicle’s intended use.
Direct TPMS is used for accurate, real-time pressure readings. However, vehicles equipped with this system are usually priced slightly higher. Indirect TPMS, on the other hand, offers slightly lower accuracy but comes at a lower cost.
The decision will depend on whether the manufacturer prioritizes accuracy or lower cost and simpler maintenance.
Those are the differences and comparisons between TPMS systems that you need to know. By understanding the differences between direct and indirect TPMS systems, we hope this will help you choose the right system for your vehicle.
For your information, TPMS systems used in vehicles must first obtain type approval certification before they can be marketed in many countries. This is because TPMS systems use sensors to wirelessly transmit pressure and temperature data to the vehicle’s control unit.
The devices must comply with specific standards and regulations regarding radio frequency usage. If you are a manufacturer or distributor looking to market TPMS products to new markets, we are ready to assist you in obtaining the necessary type approval certification.
