A tug that cannot pull is a turnaround problem
A pushback tug moves an aircraft by friction. The airplane has no reverse of its own at the gate, so the tug does the work, and it does it through a few square centimetres of rubber on each wheel. Everything the tug can achieve — drawbar pull, braking, steering accuracy while attached to a nose gear — rests on those contact patches.
That is why tire pressure on an aircraft tug is not a maintenance detail. It is part of the machine's capability. A tug with a soft tire does not merely wear rubber faster; it loses traction it was ballasted to provide, and it may pull to one side at exactly the moment the operator is making a small steering correction on a towbar.
The two wheels that have to match
Most aprons check tire pressure per wheel. On a tug, the more useful check is left against right.
When the tire on one side is lower than the other, the effective rolling radius differs. On a long pushback that shows up as a drift the operator has to correct continuously. On a machine coupled to a nose gear, that correction is applied through someone else's landing gear.
The second issue is coupling height. A conventional towbar tug or an under-fuselage cradle meets the aircraft at a height that is set by the tires. If ride height moves because one tire is soft, the coupling geometry changes, and the load path into the nose gear changes with it. The exact allowance is an engineering question for the tug and aircraft combination, not something a tire gauge should be deciding implicitly.
Neither problem is visible from the driver's seat until it is significant. A TPMS on a tug is a way of checking left against right on every shift, instead of hoping somebody measures both sides in the same hour.
What apron duty does to a tire
Ground support equipment lives in a harsher environment than its vehicle class suggests.
- Very high load at very low speed. Ballast is deliberate on a tug — it is how the machine gets traction. That weight sits on the tires whenever the machine is not moving, which is most of its life.
- Kerb strikes and apron furniture. Tugs work close to aircraft, boarding bridges, service roads and each other.
- Heat from the aircraft. Engine exhaust and brake heat at the stand are real thermal events, and a tire that is already low has less margin.
- Washdown. Aprons are cleaned, and equipment is washed. Sensors see water and cleaning agents regularly.
We specify IP68 enclosures for exactly this reason. The internal sensor is rated from −40 to +125 °C and the external type from −20 to +85 °C, which covers an apron through winter and summer.
Fleet pressure is a different problem from tire pressure
The maintenance question at an airport is rarely "is this tire low". It is "which of the ninety pieces of GSE need attention before the morning bank", and the answer has to come from somewhere other than a walk-round.
Two things make GSE different from a bus or truck fleet:
Equipment is shared. A tug is not assigned to a driver the way a taxi is. That makes unit-level records essential: a work order has to name the unit, not the operator.
Downtime propagates. A tug out of service at a peak bank does not delay one vehicle, it delays gates. The cost of a tire fault is measured in aircraft movements.
So the useful specification is not a display per cab, although that helps. It is a record per unit, in a form the GSE workshop already reads.
Retrofit across a mixed GSE fleet
Airport ground fleets are almost always mixed: tugs of two or three generations, baggage tractors, belt loaders, catering vehicles, some electric and some diesel. Replacing all of it to get tire data is not a real option, which makes retrofit the default.
A retrofit on GSE follows the same four decisions as any machine:
1. Mounting. Valve-stem sensors install fastest and suit equipment whose stems are accessible; rim-mounted sensors are the better answer where wheels are pulled regularly.
2. Power. Receivers run on DC 10–30 V, which covers both the 24 V and 12 V systems found across GSE without a converter.
3. Coverage. GSE wheel counts are small, so a single receiver covers a machine many times over. The real question is where to put the antenna so it is not shielded by ballast and steel.
4. Data path. A cab display if the machine has nothing else; a bus or serial output if the airport already collects equipment data.
Battery choice follows the wheel service interval. The external sensor uses a replaceable CR1632 rated for at least two years, which suits equipment whose wheels come off often; the internal sensor is rated for at least five to six years for machines that are opened rarely.
Display or telematics
Both are legitimate, and the choice is about who acts on the data.
A cab display gives the operator a per-wheel reading and an alarm. On an apron the display has to be glanceable: operators wear hearing protection, light is often bad, and nobody is going to read a scrolling list while attached to an aircraft. A single amber or red indication, with detail behind it, is worth more than a data-rich screen.
Integration is what turns the fleet into a managed one. Our receivers output CAN 2.0B at 250 kbps by default with a 500 ms data period, both software-configurable, and the same platform supports J1939, RS485, RS232, Modbus RTU, PROFINET and UART. If the GSE already reports to a workshop system, tire data can travel the same way and be keyed to the unit number.
A typical airport ends up with both: local alarm for the operator, records for the workshop.
What to ask before you specify
- What is the pressure accuracy? Ours is ±7 kPa, with tire temperature to ±3 °C — enough to see a slow leak between shifts.
- What is the operating temperature range of the sensor type quoted, and what is the enclosure rating?
- How long does the battery last, and can it be changed without removing the tire?
- Which protocols can the receiver output, and can you supply a message map or DBC file?
- How many wheel positions per receiver, in case the same part number has to cover larger equipment later?
We publish the numbers rather than describing them as high accuracy, and we do not claim certifications we have not obtained for a specific market. Certification for a target market is defined as part of the project.
How we work
GZVIA designs and builds the sensor, receiver, repeater, display and cloud platform in-house in Shenzhen. We serve airport ground support, port machinery and multi-axle heavy transport, and we supply port machinery builders under their own brand at around 600 units a year.
Send us the equipment list, the wheel configuration and the system that should receive the data, and we will reply with a configuration and the interface documentation.
See the applications overview, the aircraft tug installation, or the CAN bus TPMS page. To start a project, contact us.