External tire pressure sensors are an efficient and cost-effective solution to increase safety, tire service life, and operational reliability for trucks, trailers, buses, and other commercial vehicles. Especially with large wheels, such as 22.5-inch rims, correct installation plays a crucial role.
Because even a small mistake can have serious consequences: an incorrectly mounted sensor can break off, damage the valve, and in the worst case lead to sudden air loss.
In this guide, you will learn:
How to correctly install external sensors on steel and aluminum rims
why the valve material is critical
how to avoid heat damage caused by the brakes
which installation mistakes occur most frequently in practice
The main focus is on improving vehicle and road safety. In addition, environmental aspects play an important role; TPMS regulations aim to optimize fuel efficiency. A tire pressure monitoring system automatically monitors tire pressure and ensures optimal values that minimize wear and maximize tire service life.
STEP-BY-STEP GUIDE: HOW TO INSTALL EXTERNAL TPMS Sensors SUCCESSFULLY
Our sensors are specially designed for common commercial vehicle wheels (steel and aluminum). With the right tool, installation can be completed in just a few minutes.
The Tool
For installation, we recommend the special tool developed jointly with Wera.
Advantage 1: It features a preset torque (no overtightening).
Advantage 2: The special nut is slotted. This allows you to rotate the valve on the sensor without having to remove the valve cap. This prevents dirt from entering the valve core.
The Procedure
Positioning: Place the sensor onto the brass valve.
Pre-tightening: Hand-tighten the sensor until it is securely seated.
Tightening: Use the torque tool to secure the sensor in its final position.
Check: Visually inspect that the sensor is positioned within the wheel contour.
THE 3 GOLDEN RULES
OF INSTALLATION
To ensure that the sensor is securely mounted and functions reliably over the long term, three basic requirements must be met.
1. Never extend beyond the wheel contour
This is the most important safety aspect: The sensor must never protrude beyond the wheel contour.
The risk: If the sensor extends beyond the rim edge, it can catch while driving (e.g. on curbs).
The consequence: The sensor breaks off, the valve is damaged, and the vehicle suffers sudden air loss.
2. The right base: metal instead of plastic
An external sensor weighs approx. 40 grams. That may sound insignificant, but during wheel rotation it generates enormous centrifugal forces.
Not allowed: Installation on plastic valve extensions or freely hanging rubber hoses. These materials cannot withstand the load and will break.
Mandatory: Install the sensor exclusively on a solid brass valve (ideally nickel-plated) or on a firmly fixed brass extension.
3. Beware of brake heat
External sensors are made of high-temperature-resistant plastic, but they have physical limits.
The problem: Brake discs radiate intense heat—especially when stationary after a downhill drive (heat build-up).
The solution: Observe the specified minimum distance from the heat source (brake) to prevent the sensor from melting.
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IMPORTANT FAQs
How Can I Tell Whether My Valve Extension Is Suitable for External Sensors?
Our external truck valve-mounted TPMS sensor is suitable for most wheel designs. Suitable valve extensions are solid, firmly fixed brass extensions.
Not suitable: plastic, rubber, or flexible long extensions.
If the valve moves or vibrates when lightly touched, it is not suitable.
Can External TPMS Sensors Affect Tire Balance or Driving Behavior in Trucks and Commercial Vehicles?
In principle, no, but there are a few important details:
The sensors weigh approx. 40 g and are positioned radially very close to the axis of rotation.
Due to the small lever arm, the impact on wheel balance is minimal.
With correct installation, no rebalancing is usually required.
Exceptional cases in which balancing may be advisable:
High-speed trailers over 130 km/h
Extremely sensitive wheel and tire combinations
Defective or eccentric valves
In 99% of cases, however, no adjustment is necessary.
How Long Does the Battery of an External TPMS Sensor Last — and Can It Be Replaced?
Battery life is typically around 5 years, depending on:
daily driving time
transmission intervals
ambient temperature
sensor quality
In high-quality systems, the battery is not replaceable because:
the sensor is hermetically sealed (protection against dust, water, salt, and brake dust)
opening the sensor would compromise its sealing
the risk of malfunctions would increase
What Should You Do If a Sensor Does Not Transmit Data Despite Correct Installation?
Possible causes & solutions:
Wait for the run-on time: Some systems only activate transmission once a certain speed has been reached.
Blocked antenna paths: Metallic wheel beds, long trailers, or internal mounting positions can partially obstruct the signal – a repeater can help.
Software-side decoupling: The sensor may need to be re-paired in the control unit or gateway.
Thermal damage: If a sensor was mounted close to the brake, it may have failed due to heat.
Defective valve: If air is leaking slightly, the measurement may become unstable.
Can External TPMS Sensors Be Used on Dual Tires?
Yes – however, additional installation conditions must be met:
The sensor must not rub against the inner rim or the dual tire.
Eccentric positioning of the sensor helps to avoid tight clearances.
Brass extensions must be fixed particularly securely.
Heat buildup is higher on inner wheels → check clearance.
In practice, installation on dual tires is usually possible without issues when high-quality extensions are used.
