WORKSHOP: Only have valves on the inside of your wheel rims? Then the task of changing tyre pressures can be more challenging. Yet it is possible to retrofit these on the outside without taking off the tyre.

Around half of the tractors supplied for our tests have their tyre valve positioned on the inside of the rim, making adjusting the pressure to suit different tasks and conditions that bit more tricky than it needs to be.

One neat alternative is to fit a tyre pressure control system, which will regulate the tyre pressure in all four wheels (and can also do the same for trailed kit if it has the correct hardware) at the press of a button. But such convenience comes at a price: anything from £5,000 to £17,000, depending on the make and level of sophistication — refer back to our comparative test in the 9/2022 issue for more details on that. A significantly cheaper alternative is to use an airline, which plugs into the red air brake coupling on the tractor for the air supply. One such system is the Airbooster Plus set from PTG. The kit comprises 5.0m of hose, a pressure gauge, four screw-on nipples and an adapter for the red brake line coupler

The pressure gauge and the adapter are safely stored in a small plastic case. The hose has a special coupling at one end, and this will only connect to the pressure
gauge device. The reason for this is a small overpressure valve at the end of the hose that cuts the air supply at 3.5 bar in case the user forgets to close the tap in time.

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