How Does Motorcycle TPMS Work? Sensors, Radio, Alarm A motorcycle TPMS is three parts: a sensor on the valve, a radio link off the wheel, and something that decides when to alarm. Here is how each one works.

The three parts of any TPMS

Every tyre-pressure monitoring system, on any vehicle, is the same three things arranged differently: something that measures, something that carries the measurement away from a spinning wheel, and something that decides whether what arrived is worth alarming about.

The interesting part is not any single component. It is that the second and third stages are where manufacturers make their real design choices, and those choices are what you are actually buying. Here is how each stage works on a motorcycle, and where the two common radio approaches diverge.

Stage one — measuring pressure and temperature

The sensor is a small sealed body that screws onto the valve stem, in place of the valve cap, in the valve-stem replacement style we build. Inside it there is a pressure-sensing element and a temperature sensor, a microcontroller, a radio and a battery.

Both quantities matter, and for a reason that is easy to miss. A tyre's pressure rises as it heats up: a tyre that reads correctly cold will read higher after twenty minutes of riding, and a tyre that reads correctly hot will read low when the bike is parked overnight. A system that reports pressure without temperature cannot tell you whether a reading is being taken cold or hot, and that makes the alarm thresholds hard to set sensibly. Reporting both is what lets the alarm logic use a temperature-compensated reference.

The measurement chain also has to be calibrated. An uncalibrated pressure element drifts, and a drifted sensor produces either nuisance alarms or missed ones. That is why every sensor we ship is pressure-calibrated individually on our own test software rather than spot-checked by batch.

Stage two — getting the data off the wheel

This is where the two product families separate.

The sub-GHz route. The sensor transmits on a licence-free band — 433.92 MHz in most of the world, 315 MHz in parts of the Americas — to a dedicated receiver, usually a display on the handlebar or a box wired into the vehicle. The receiver is part of the product, and the rider reads pressure from it. This is the arrangement that dominates trucks, trailers and fleet equipment, and it has never been a comfortable fit on a motorcycle because there is nowhere neat to put a display and nobody wants to pull the loom apart.

The Bluetooth route. The sensor transmits in the 2.4 GHz ISM band — 2400 MHz to 2483.5 MHz on BLE 4.1 — and a phone running an app receives it. There is no dedicated receiver and no harness; the rider's phone is the display. Our sensors take this route, with 3 dBm transmit power, a 1 Mbps air rate and −95 dBm receiver sensitivity at 1 Mbps.

Neither route is inherently more accurate. Both carry the same measurement. What differs is what has to be installed on the vehicle, and who owns the interface afterwards. Our optional UART and CAN receivers exist for the cases where a Bluetooth link is not the right answer and the vehicle needs a wired output.

Stage three — receiving, deciding and alarming

A pressure number on its own is not a monitoring system. The value has to be compared against something, and the comparison has to allow for the fact that tyres behave normally in ways that look abnormal.

Three things usually sit in that logic.

Thresholds. A low-pressure limit, and often a high-pressure limit as well, because an over-inflated tyre is also a problem and a sensor can catch a slow over-pressure from heat.

Temperature compensation. Because pressure rises with temperature, a fixed low-pressure threshold can be triggered on a cold morning and missed on a hot afternoon. Some systems do this compensation and some leave it to the rider's judgement.

The missing-reading case. Radios lose packets. Every Bluetooth system will occasionally fail to receive a transmission. What the app or display does at that moment is a design decision, and it is the one that separates a trustworthy product from an untrustworthy one. Showing the last known value with no indication that it is stale is the worst option available. Saying nothing is the second worst.

In a Bluetooth product, this logic usually lives in the app, which is why the app is not an accessory to a BLE TPMS — it is half of the system. The app page covers how ours is structured for Android and for per-project iOS work.

The two radio routes, side by side

	433.92 / 315 MHz	BLE 2.4 GHz
Receiver on the vehicle	Required	Not required
What the rider looks at	Dedicated display	Phone app
Typical range	Long vehicle, trailer, machine	Sensor to phone
Regional band variants	Yes, 433.92 and 315 MHz	One band worldwide
Alarm logic sits in	Receiver firmware	App or host software
Wiring into the bike	Usually necessary	None
Works with the phone off	Yes	No live readings
Common fit	Trucks, trailers, fleet	Two-wheelers, e-bikes, ATVs

Why temperature is measured as well as pressure

There is a second reason beyond threshold compensation: a temperature reading helps diagnose the cause rather than just the symptom. A slow drop in pressure with normal temperature suggests a puncture or a leaking valve. Pressure rising together with temperature suggests the tyre is working hard or the brake is heating the rim. A sudden rise in both, on one wheel, is worth stopping for.

That is the difference between a gauge and a monitoring system. A gauge gives you a number; a monitoring system gives you a number in context and tells you when the context has changed.

What a TPMS does not do

It is worth being clear about the limits, because expectations shape complaints.

It does not inflate anything. It does not seal a puncture. It measures at the valve stem, so a sensor is only as good as the valve it is fitted to — a leaking valve gives a false low reading regardless of sensor quality. It cannot see tyre tread or sidewall damage. And a sensor that has stopped transmitting looks exactly like a tyre that is fine, unless the display or app is honest about the gap.

Where we stand

Our sensors report pressure, temperature and alarm state over BLE 4.1 in the 2.4 GHz band, powered by a CR1632 cell that the user can replace without re-pairing the sensor. Operating temperature is −20 °C to +80 °C, storage −40 °C to +85 °C, humidity 5–95% non-condensing. They are built for two-, three- and four-wheel vehicles.

We make them in Shenzhen, at a capacity of 30,000 sensor units a month, with more than 10,000 sets a month going into the Chinese two-wheeler aftermarket. Eight in-house test steps run before shipping: pressure calibration on every unit, water immersion, RF range, protocol verification, powered ageing, battery current, appearance and dimensions, and a full wheel-position system test. Certification is handled per market and per project, and we will state the current position for your destination in writing.

If you want the measurement and alarm chain explained against your own vehicle, send us the vehicle, the wheel count and the market. The sensor specification is on the BPU100 product page.