Our answers to the questions
we get asked the most


No, PSI monitors the pressure in the trailer tyres and re-inflates to optimum pressure when there is loss of air.

PSI is currently only a commercial trailer solution, however, developments are to follow for trucks.

In the 1st instance yes, but if the incoming system pressure is higher than 6 bar when the trailer is uncoupled the pump will be active if the tyre pressure drops.

The warning light will be flashing – the light is visible for the driver via the back mirror view – the faster the light is flashing, the more sever the puncture, if the light is constantly illuminated there is a very severe puncture which the system cannot maintain and the driver must stop immediately.

There is a non-return valve in the rotary union which prevents air from feeding back from the tyre.

The system works with air from the truck and a feed is taken from the air supply and is then transferred to the control box to step the pressure up.

No – There is a generator in the control box which powers the light with the exhaust air from the step up pump.

You can simply replace with a new hose and the system will re-inflate the tyre to optimum pressure OR it is possible to replace with one of the other hoses from the trailer, where there is no leak, for the remainder of the journey as the non-return valve will prevent the tyre with no hose from losing pressure.

When the Systems starts working the warning light will flash to inform you of a problem

A trailer with 5 axles is the maximum.

The air supply to the control box, as this needs to be at least 6 bar or 80psi.

No, only the Tyre Hose must be unscrewed

When the tyres are cooling down at the end of the journey and in the evening.

Only when someone is carrying out work on the system


No, there is a valve in the rotary union which is operated by the tyre hose when connected this allows air to pass from system to tyre.

The only time the system has to be drained is when you carry out maintenance on the wheel end such as when you are cleaning bearings or taking the hub off to change the rotary union (which is typically between 200,000 – 300,000 Kilometres).

The output pressure must be checked once every 6 months, the way to do this is put a digital pressure gauge on one of the outputs from control box and blanking the other two outputs off OR alternatively you unscrew the hose from the rotary union and connect a digital gauge to the rotary union end (we can supply a kit for this).


Yes, there is a special application available for twin wheel configurated trailers.

No, it is dependant on which axle the system is for, for further advice on this please contact one of the team.

Customer – where to order

PSI is available via all European trailer OEMs, however you need to ensure they request with the nominated axle OEM to prepare the axles for tyre inflation. For further information please contact our team.

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