Tire Pressure Monitoring System (TPMS)

We are seeing more and more vehicles come to us with Tire Pressure Monitoring (TPM) systems. These systems have special valve stems and a device at each wheel that receives a signal from the valve stem to let the driver know of any air pressure problems in any of the four wheels.

These monitors can be expensive and touchy to replace. A tire technician needs to be aware of the presence of this monitoring device prior to dismounting a tire from a wheel. After the tire is placed back on the vehicle, the TPM system frequently must be reset to let the car "learn" about the new wheel and tire.

How It's done

Breaking tire bead Dismounting tire Lip on wheel rim
It is critical that the tech does not break the bead at the valve. When dismounting the tire, care must be taken to avoid hooking the TPM sender. Many rims now have an extra groove in the wheel to help keep the bead seated even in a sudden loss of air.
TPM sensor on rim TPM sensor TPM Sensor
The TPM sits nearly flush with the inner wheel. There are small offsets on the back to hold it off the wheel. TPM valves must be changed out every few years. Here you can see a date on the bottom. In some models the batteries can be changed. This is the bottom of the TPM valve. You can see the small bumps that maintain the offset.
Tire Balancing

If the vehicle has a TPM system that "learns," the tech should check the air pressure in all four tires and reset the TPM system to the correct pressure. In systems that take time (5 -10 minutes) to learn and reset themselves, the customer should be notified of this and asked to return the vehicle if the system has not "learned" and reset itself.

The vehicle should not be driven at highway speeds with the TPM system non-functional.

Once the wheel is remounted it should be statically and dynamically balanced.