Even the keenest proponent of good tyre inflation management will admit that changing pressures for every different situation is not always practical.

But that limitation goes out of the window when the tractor has a built-in tyre inflation system – and all the more so when it allows tyre pressure adjustment from nothing more than the touch of a button.

With the integral systems now available for the Mercedes-Benz Unimog and Fendt 900 Vario series tractors, tyre pressure management really is that simple. It means changing inflation settings during the course of the day becomes a practical reality.

Technology overkill? Not necessarily. Manufacturers have made huge progress in recent years developing large volume tyres that will cope with heavier tractors, putting out massive amounts of power and torque that can run at faster speeds on the road.

While they have the carcass strength and integrity to cope with those demanding parameters, tyres like the Continental Super Volume Tyre (SVT) from CGS can also operate at remarkably low inflation pressures.

But to get the best from your tyres, inflation pressure needs to be lowered from the levels necessary for extended road work hauling an implement to the field to the optimum for traction, self-cleaning and the outfit’s impact on the soil having passed through the field gate.

It’s possible to do that manually by opening the valves and checking pressures with a gauge as long as there is a compressor available to inflate the tyres for the journey home. But with driver schedules invariably under pressure to get the job done, this is not a practical solution.

However, with the Central Tyre Inflation system (CTI) developed by Mercedes-Benz for the Unimog vehicle installed, all four tyres can be deflated and inflated from the cab – and for those in a real hurry or with little patience this can even be done on the move.

The resulting increase in length and width of the tyre-to-soil contact area will not only ease rolling resistance and minimise the depth of any soil compaction by spreading the weight of vehicle and implement or load over as big an area as possible. It will also enable best possible traction and self-cleaning performance for the conditions.

The same goes for the tyre inflation management system developed for the Fendt 900 Vario tractor range – only in this case, it also be used to change tyre pressures on a trailer or other towed equipment.

The factory-installed tyre pressure control system comprises a modified engine-driven air compressor, a pressure control valve for each axle and special hubs incorporating a ring-shaped rotary union through which air can pass from the compressor into the tyre.

There are no exposed air feed lines such as those seen with retro-fit systems on self-propelled flotation spreaders or slurry tankers and the rotary union is designed to last the lifetime of the tractor, says Fendt. And like the Unimog, it can be used when the vehicle is in motion.

Tyre pressure can be increased by 1 bar in less than seven minutes; it takes just two minutes to reduce tyre pressure by the same amount. Moreover, the system can utilise the Varioterminal’s Isobus compliance to also regulate the pressure of tyres on a suitably-equipped trailer, slurry tanker or spreader.

Case Study: Dave Chandler, Staffordshire

Midlands lime spreading contractor Dave Chandler runs a long wheelbase (3.6m) Unimog U400 and with a gross vehicle weight of some 12.5t, the capacity of the machine and its 80kph road speed provide high work rates.

But it also presents a threat to soil structure when conditions are less than ideal underfoot.

Despite that, Mr Chandler says the vehicle has been welcomed by farmers throughout the region, knowing that by using the Central Tyre Inflation system, he can minimise the impact of its passage across fields by altering pressure settings for the 540/65R30 Pirelli TM800 tyres from Trelleborg that are fitted all round.

The system, which is an option on all Unimogs – the U300, U400 and U500, including the agricultural specification models fitted with three-point linkage and pto – can be used to deflate or inflate the tyres one axle at a time or simultaneously from the driver’s seat.