The question installers actually ask
Not "how far does it transmit" but: **"if I have to choose where to put the sensor, does it
matter which wheel?"** On a dual-tyre axle you must choose. On a machine where the receiver can
only go in one place, you must choose. So we measured it.
How the data was collected
Two port AGVs of the same type, no repeater, receiver in the same location. One run monitored
only the four right-hand wheels, the other only the four left-hand wheels. Each run is
18–21 minutes of continuous CAN logging.
Method for loss: each sensor increments a counter in every packet and cycles it `0x00` to `0x28`.
A jump in the sequence means lost packets; loss = lost / (received + lost). Same method as our
published packet-loss test.
Result 1: left side versus right side (port AGV)
| Wheel position | Right side (no repeater) | Left side (no repeater) |
|---|---|---|
| 0x11 | 10.59% | 10.62% |
| 0x12 | 8.45% | 14.98% |
| 0x13 | 5.45% | 6.47% |
| 0x14 | 8.90% | 6.64% |
| 0x21 | 8.31% | 37.61% ⚠️ |
| 0x24 | 7.87% | 13.36% |
| Average | 8.3% | 15.0% |
Right side was better on average, and 0x13 was the strongest position in both runs.
⚠️ One number in that table is not a radio result. Position 0x21 on the left side shows 37.61%
with 324 repeated counter values — the counter sat still while packets kept arriving. That is a
sensor/forwarding anomaly, not a radio path that suddenly got worse. Publishing it as "signal
quality" would be wrong, so we are flagging it instead.
Result 2: corner mounting versus middle mounting (tractor, 4 wheels)
| Run | Average loss | Range | What the log also shows |
|---|---|---|---|
| Corner mounting | 22.1% | 20.5–22.5% | Even loss across all four positions |
| Middle mounting | not comparable | — | Two positions repeated the same counter 225 times; the file also contains logging gaps of ~3,000 s (two sessions joined) |
The middle-mounting file cannot be turned into a loss number honestly: a 3,000-second gap is a
logging break, not 1,500 lost packets per wheel. We could have published "85% loss" from it. It
would have been false. What we can say is that in this dataset the corner-mounted tractor ran at
about 22% loss on all four wheels — high enough that this machine needed a different receiver
position, not a different sensor.
What the numbers mean in practice
1. Position beats sensitivity. Moving the receiver a metre changes the loss rate more than
changing sensor orientation does. On the AGV, the same sensor type went from 5.45% to 10.59%
depending only on which side of the machine it was on.
2. The far corner is where it breaks first. In the tractor run, all four wheels degraded
together — the receiver itself was in a poor place, not one sensor.
3. A repeater is a placement fix, not a sensitivity fix. It puts a listener where the radio
path is short (see our repeater test: it did not reduce total loss, it reduced *confirmed* loss).
4. Watch the counter, not just the alarm. A position that repeats the same counter is a fault
you will not see in the pressure value. That is why our receiver reports sensor status
separately.
Pre-installation checklist
- [ ] Can the receiver be mounted low, in the open, near the axles rather than behind the cab?
- [ ] Is any wheel behind a steel structure from the receiver's point of view?
- [ ] On a dual-tyre axle, are both tyres of the pair measured, or only the outer one?
- [ ] Does the wheel map name positions consistently (axle / side / inner-outer)?
- [ ] If a position must sit in a bad spot, is a repeater available at the front axle centre?
- [ ] After installation: log 10 minutes of CAN data and run the counter check — not just a visual
check of the screen.
FAQ
Which wheel is usually worst? In our port AGV data, positions on the far side from the receiver,
and the one closest to a large steel structure. There is no universal "bad wheel" — it is defined by
the receiver position.
Should I fit the sensor inside or outside the tyre? These are separate products: the external
valve sensor needs no tyre removal, the internal band sensor needs the band cut to the rim
circumference. Placement question above is about radio, not mounting style.
Do I need a repeater if one position is bad? Possibly, but change the receiver position first —
it is free.
Can you review our wheel map? Yes: send the axle layout and the intended receiver position, and
we will say which positions are likely to be weak before anything is installed.