Can You Change Tires at Home Without Damaging TPMS Sensors?

Where the sensor sits

The tire makers' care manual describes the common layout: tire and wheel assemblies with a tire pressure monitoring system may have a sensor that is attached to or is part of the valve assembly. From outside you see an ordinary-looking valve stem. Inside the rim, the sensor sits at the base of that stem.

That is exactly the zone a tire tool passes through. The bead-breaker shoe pushes the bead inward toward the drop center, and the bar or mount/demount head travels around the rim edge. Either one can press a bead or a steel tip against the sensor.

What the documents say, and what they leave open

The tire makers. Their mounting bulletin gives one instruction on the subject: on wheels with TPMS sensors it is recommended to replace all components that are included in the TPMS valve replacement kit, and the reader is referred to the vehicle manufacturer's TPMS service requirements. No bead-breaker position is named.

A machine maker. Hunter Engineering publishes a service form for TPMS wheels on its own table-top tire changers. It is the most concrete document we found, and it shows that the right position depends on the tool:

The form also offers an optional step before demounting: loosen the sensor nut and drop the sensor into the tire, then retrieve it once the tire is off. On refitting it asks for new o-rings, a torque checked against the service manual, and a check of the sensor with a handheld scanner before and after the job.

The manual changer. In the parts of the copy of the reference changer's owner's manual that we could read, pressure sensors are not mentioned, and we found no other manual changer document with a TPMS procedure. Hunter's positions are written for Hunter machines and cannot simply be copied to a floor post with a lever bar.

What follows for a manual tire changer

What follows here is our own cautious reading of the documents above, not a maker's instruction:

• Look up the wheel first. The vehicle manufacturer's service information says where the sensor sits and how it is fastened. The tire makers point to it, and so do we.
• Break the beads away from the valve. Every position on Hunter's form keeps the breaking tool at least a quarter turn from the valve stem. Set the shoe of the bead breaker on the far side of the wheel and never at the valve. The working steps are under how to break a tire bead.
• Know where the valve is at every pull of the bar. A bar tip that dips into the rim near the valve can reach the sensor. Start and finish the lever work away from it; the sequence on a floor-post changer is described under how to use a manual tire changer.
• Keep the opposite bead in the drop center when you lever, as on any wheel, so that no extra force is needed near the valve. The drop center rule comes from the tire makers and is explained under how to remove a tire from a rim.
• Do not force anything. A bead that will not move near the valve is a reason to stop and look inside, not to add weight to the bar.

The service kit comes with every new tire

The tire makers treat the valve of a TPMS wheel like any other valve: it is serviced when the tire is replaced. Their care manual says:

• When new tires are installed, it is recommended to also replace all components that are included in the TPMS valve replacement kit.
• Whenever the sensor is disassembled for any reason, install a new TPMS replacement kit.
• Always replace any damaged sensor.
• If the TPMS valve is replaced by a conventional valve, the TPMS will not function.

Which kit fits depends on the sensor, so buy it by vehicle and sensor type. Tightening values belong to the same service information; Hunter's form names a figure for its example and adds that it has to be verified with the service manual.

When a shop is the better choice

Wheels with pressure sensors are often the wheels a manual changer is not specified for anyway. The reference machine is specified up to 16 in., and the tire makers ask for equipment designed for low aspect ratio, high performance tires and wheels; see can a manual tire changer do low-profile tires. Run-flat tires have a mounting bulletin of their own, and the care manual says a vehicle on run-flat tires must have an operational TPMS. If your wheels fall into one of these groups, the sensor question is settled by the larger one: they go to a shop.

For ordinary wheels up to 16 in. with a valve-mounted sensor, the job can be done at home with the care described above and a new valve kit. Rim marks are a separate risk, covered under will a manual tire changer scratch alloy rims. The term TPMS and the parts of the rim are explained in the glossary, and more short answers are on the questions page.