The short answer
One GZVIA receiver addresses up to 256 wheel positions. If you are monitoring 4 to 30 wheels — a bus, a truck, a reach stacker, a rubber-tyred gantry crane — a single receiver is usually the whole system, and the number never enters the conversation.
The number starts to matter above 60 wheels, and at that point the question changes. The useful question is not "how many sensors can one receiver handle" but "what does it take to handle my wheel count reliably".
Capacity is three separate budgets
Capacity lives in three places, and a supplier who only discusses the first has not sized your system.
1. Address space. How many sensor IDs the receiver can hold and report. Ours is 256. This is the easy one — it is a table in firmware.
2. Radio air time. Every sensor transmits on a shared 433.92 MHz licence-free channel. The default data period is 500 ms and is software-configurable. Multiply sensors by frames and you get the load. Doubling the sensor count at the same period doubles the traffic; if your update rate matters more than your sensor count, the period is the knob to turn. What you cannot have is the fastest possible update on every wheel of a very large machine, because the channel is shared.
3. The physical radio path. The receiver does not care where the wheels are; the radio link does. Steel structure, wheel wells, rotating rims, an articulating trailer and a 30-metre chassis all attenuate the signal. In our own testing the link reaches at least 100 m in free air — and a loaded machine is not free air. This is the budget that limits most projects.
What a large machine actually looks like
Two real configurations make the point.
- 160-wheel beam carrier, in production. Two receivers, twelve repeaters, 160 sensors — roughly one repeater per thirteen wheel positions — with ten machines delivered in this configuration. The repeaters are not padding; without them the far end of the carrier is not heard reliably.
- Largest single machine we have instrumented. 224 wheels across 28 axles, eight positions per axle. Receiver capacity was never the constraint here either.
Both projects demanded more work on repeater placement, harness routing and commissioning discipline than on sensor count.
Why capacity is the wrong first question
Lead with it and you get an answer that is technically true and commercially useless. Three things get missed.
Wheel positions versus wheel count. A spare, a lifting axle, or a set of wheels that rotates out of service all change the number. A quote built on "one sensor per wheel" is often short. Ask how the count was derived.
Repeaters. The cheapest quote frequently omits them, because they only become obviously necessary once the machine exists. Repeater count is the single most common line that changes after the order.
Commissioning and spares. At 200-plus positions, mapping sensor IDs to physical wheels is real work, and it has to be repeatable by your own maintenance team three years later. If the configuration record lives only in the supplier's spreadsheet, every tire service turns into a phone call.
How to size it in one exchange
Send the following and a competent supplier can answer without guessing:
- axle layout and positions per axle, not just a single total
- whether any position rotates, lifts or swaps
- chassis type: rigid, articulating, or a trailer with its own frame
- where the display or gateway will sit, and how far that is from the furthest wheel
- supply voltage — our equipment runs on DC 10–30 V
- the protocol your controller needs: CAN 2.0B at 250 kbps, J1939, RS485, RS232, Modbus RTU, PROFINET or UART
- what must happen on an alarm: a buzzer, a dashboard lamp, or a message on the vehicle bus
With those seven, the sensor count, the repeater count and the configuration come out of engineering rather than sales.
Planning rules that hold up in the field
- Put the receiver where it can hear wheels, not where the wiring is convenient. A cabinet in the middle of a machine is often a worse radio location than the outside skin.
- Plan repeaters as part of the electrical architecture. They need power and a mounting point, and both are far cheaper to design in than to retrofit.
- Treat the sensor ID list as a deliverable: mapped to axle and position, in a format your workshop can edit.
- Decide the update period before you fix the sensor count. If a slow leak has to be caught on a machine with 200 positions, alarm logic and period have to be designed together.
- Test at full wheel count. We run full-position system integration before shipment precisely because a 160-position machine does not behave like a 4-position one.
What we actually verify
Worth stating plainly, because it separates a manufacturer from a reseller. We verify pressure calibration on every unit, run water immersion, verify the radio link over distance, run full wheel-count integration, age the electronics under power, and verify CAN and serial protocol behaviour. Those results ship with the configuration record.
Read the TR100 receiver specification, or see the 160-wheel beam carrier installation for a configuration in service. If interface detail is your question, the CAN bus TPMS page covers protocols, message maps and register maps.
The one-line answer
One receiver addresses 256 positions; how many you can actually monitor on a given machine depends on air time and radio path, and that answer is designed, not quoted. Send us your axle layout and we will come back with the receiver and repeater count for it.