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Review: Michelin shows off central tyre inflation package

Representing a culmination of technology driven by customer demand, Michelin has revealed a complete solution for on the go management of tyre pressures. James Rickard reports.


The benefits of operating tractor tyres at the right pressures in the field and on the road are well documented. However, this in itself presents a challenge to farmers and contractors, as the two situations require contradicting setups if the tyre’s capabilities are to be maximised.


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To preserve soil health, reduce compaction, limit wheelslip and increase traction, tyres should ideally but run at low pressures. Conversely, road travel requires high pressure tyres to keep rolling resistance to a minimum, minimise fuel consumption and offer stability. Independent studies conducted at Harper Adams University and the University of Illinois have shown at least a 4 per cent increase in crop yields can be achieved by using the correct tyre pressures.


While tyre pressures can be altered, it is often the inconvenience of doing this which prevents farmers and contractors from making the most of their tyres. To get around this, many farmers and contractors are starting to fit central tyre inflation systems (CTIS), which allows on the go adjustment of tyre pressures. And although several companies offer retro-fitable systems, only a small number of tractor manufacturers offer an integrated system with the list limited to Fendt and Claas, and only on their bigger tractors.


With this in mind, Michelin has come up with an all-inclusive approach to the problem. Called Zen@Terra, the aim is to offer a complete package which allows farmers and contractors to pre-plan tyre pressure configurations, allow alteration of tyre pressures on the go and maximise the latest tyre technology.

Technology involved

Four main ingredients make up the Zen@Terra package; Michelin’s latest EvoBib tyres, the central tyre inflation system (CTIS) developed by PTG, the real time usage display and an online tyre pressure management portal. Primarily it is the tyre technology which has spurred Michelin on to invest in CTIS. While CTIS can be used to get more out of its current range of tyres, particularly its AxioBib range, it is its new ‘two in one’ EvoBib range which has been specifically designed to work with a CTIS.


First previewed at the 2017 French SIMA show, EvoBib can exist in two distinct forms; low pressure for field work, and high pressure for road work. Key to the tyre’s design is its tread pattern which sees a secondary set of lugs come in contact with the ground when pressures are dropped below 1.2bar (see pictures below). Michelin says when operating at 0.8bar, EvoBib’s contact patch is 20 per cent greater than that of an equivalent sized 710/70 R42 AxioBib tyre, effectively creating an 800mm wide tyre. Traction is also claimed to increase by 30 per cent, equating to 30 per cent greater productivity and 20hp more usable power. As a result, Michelin says this opens up the potential for either capitalising on the extra productivity, or it also presents the possibility of downsizing tractors.


When inflated to road pressures, the contact patch reduces, with the weight of the tractor resting on a dense ring of tread blocks within the centre of the tyre tread. This, it says, reduces rolling resistance and noise, while maintaining stability and comfort.


EvoBibs are approximately 45 per cent more expensive than equivalent sized AxioBibs, which suggests a certain scale of operations is required if the Zen@Terra package is to pay for itself.

EvoBib at field pressure

EvoBib tyre at field pressure.

EvoBib tyre at road pressure.

EvoBib tyre at road pressure.

EvoBib tyre sizes

  • 710/70 R42
  • 600/70 R30
  • 710/75 R42
  • 650/65 R34
  • 650/60 R34 (available June 2019)

About the CTIS

The central tyre inflation system (CTIS) is the result of Michelin acquiring CTIS specialist PTG. Founded in 1991, PTG equipment is currently available in the UK through TractAir.


Initial availability of the complete Zen@Terra package will be in Germany, Austria, France, Belgium, Switzerland, Luxembourg and the Netherlands, with the UK and Scandinavia receiving the technology in Q2 of next year. Michelin is aiming for tractor dealers to fit the CTIS with support from PTG’s importer in that region – TractAir in the UK’s case. Due to the complexity, it will not be available as a kit for customers to fit.


Depending on requirements and type of axles, PTG offers two main types of CTIS; one which sees pipes routed on the outside of the tyres (pictured below), and one which sees air routed through the centre of the tractor’s axles. The former allows the pipes to be quickly disconnected and the wheels removed.


Suited for tractors 200hp and above, the system can be retro-fitted to older tractors or can be ordered with a new tractor. Due to the differing elements of the package from tractor to tractor, price of Zen@Terra is about €20-26,000. Compared to other CTIS on the market, Michelin says by offering a complete package (tyres, CTIS and tyre management) it can assure the fitment and the operation of the system.

External CTIS piping.

External CTIS piping.

Internal CTIS piping.

Internal CTIS piping.

Control and management

Control of the CTIS is via an IsoBus interface displayed on a tractor’s own, or third party terminal.


From here, job type (drilling, tanking, mowing, etc) can be selected, along with the situation (road or field). Once selected, the system does the rest for you, automatically inflating or deflating the tyres to the appropriate pressures.

For implements with hoppers or tanks, empty, half full and full modes can also be selected, which will consequently alter tyre pressures accordingly. A hillside working mode can also be selected, which will increase tyre pressures to boost stability.


Furthermore, a traction boost mode can be used, which allows up to three minutes of ultra-low tyre pressures, to get you through a ’sticky’ patch. During tyre pressure adjustment, the actual and target pressures are displayed. Also, if the speed of the tractor strays out of the safe working window of the selected tyre pressure, visual and audio alarms will go off.


Before operation, job types need to be setup via Michelin’s online web portal. Here you can set tyre pressures based on the tractor, axle loads, the implement, working speed, ballast used, etc. Once set-up, the configuration for each job type can be saved, and then transferred via an app to the tractor’s terminal. Each configuration will also be checked by Michelin, which it says will be offering personalised support of the product.


For now, the system will only adjust tractor tyre pressures, however, the manufacturer is extending the system to work with trailed implements next year.

control pic

In-cab Zen@Terra control.

What a farmer thinks

What a farmer thinks

Zen@Terra is currently being evaluated by six farmers across Germany, France, Belgium and the Netherlands.


To find out how it has been performing in the real world, we caught up with Belgian farmer, contractor and machinery dealer Antoine Rouxhet.


Based in Spa, Mr Rouxhet has been using Zen@Terra on a John Deere 6230R since April, and has already seen big differences in both crop production and operating efficiency. “We produce about 200 hectares per year of corn silage,” he says. “Where tractors and tankers have run in the fields without the use of CTIS, you can visually see a difference in crop heights, with the crop looking much healthier in the areas of less compacted ground.


“Traction has also massively improved with the ultra-low pressures at which the EvoBib tyres can run - we are easily seeing 20 per cent improvements, which means we can run with less ballast.”


However, the lengthy time the tyres took to inflate using the tractor’s own air compressor was something which needed addressing quickly, he says. “It was taking about 15 minutes with the tractor’s own compressor, which is just not workable when you are in and out of the field with a 23cu.m slurry tanker.”


To fix this, Mr Rouxhet’s dealership fitted a bespoke compressor capable of pumping 1,000l/min of air. He says; “The tyres can now be back up to road pressure in under three minutes, which can be started just before the tanker empties.”


Michelin says extra air tanks could also be fitted, which would allow air to build up before it is needed, allowing quicker inflating times.

Have a look at Michelin's manufacturer account

Michelin agricultural tyres deliver measurable benefits and improve the performance of tractors, harvesting machines, sprayers, trailers and other farming vehicles. Our innovative, sustainable products have soil preservation at their heart to help farmers increase their yield without damaging the ground they work on.


Thanks to Michelin Ultraflex Technology, our tyres offer a greater footprint and can operate at very low pressures. Michelin has been working with agricultural professionals for more than a century.


Through our expertise and skills, we assist farmers to optimise operating costs, save fuel and improve crop yields, while reducing soil compaction.

Tech Spec
Power (hp)200 and above
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