The Claas Axion 820 with conventional tyres under test conditions –the small fuel tank on the front linkage making it possible to precisely measure fuel use, the large display screen on top of the cab displaying the draught figure from the load sensing rear linkage.

The demonstration was organised by the Michelin Agricultural Contractor Panel, sponsored by Michelin and supported by Claas, and was intended to demonstrate the benefits of using high specification tyres and of setting up equipment correctly in order to show that it is possible to save fuel and maximise work rates.

A large number of contractors and farmers were invited and specialists from Michelin and Claas were on hand to explain theories and answer questions. Dr Andy Scarlett from Scarlett Research Ltd, a specialist in agricultural tyres and traction had set up various demonstrations featuring tractors loaded with scientific measuring equipment to provide live information while the tractors were working. Two activities were studied – a Claas Arion 640 pulling a seven furrow reversible Lemken vari-width plough and another similar tractor pulling two identical trailers loaded to exactly the same total weights but travelling on different types of tyres.

Both tractors had digital information displays on top of the cabs and these indicated the draught or pull being generated in order to pull the loads – the force was measured using precise measuring equipment between the tractors’ standard hitch systems and the two loads. A small fuel tank was mounted on the front weights of both tractors and the fuel for the demonstrations was taken from this rather than the tractors’ main tanks, so that the fuel use could also be precisely measured.

The tractor and plough were demonstrated first on conventional Michelin Agribib 520/85R42 rear tyres, inflated to 25.00psi and 420/85R30 fronts, inflated to 20.00psi. The wheels and tyres were then swapped to the top specification Michelin XEOBIB VF710/60R42 rears, that can carry out the same work at just 12.50psi and VF600/60R30 fronts running at 9.00psi. The tractor was driven to exert the same level of draught on both sets of tyres, verified by the digital display on the cab roof.

The main difference between the tyres was that the top specification XEOBIBs have been developed to carry the same loads but at much lower pressures by exerting a much larger footprint on the ground. The larger ground contact area means that ground pressure and soil compaction are reduced, grip is increased and wheel slip is reduced.

In practice the difference was clear to see, the higher specification tyres providing a higher ground speed, and reducing the wheel slip from 14.0 percent to just 9.2 percent. The resulting useful power was 105kW on the conventional tyres and 115kW on the XEOBIBs.

The trailer demonstration was similar, although this time it was the trailer tyres that were changed between conventional “super-single” Michelin 445/65R22.5, as fitted on many farm corn trailers, and Michelin flotation 560/60R22.5. The difference between the tyres was immediately noticeable, the flotation tyres bulging at the bottom and very obviously having a much larger contact area. The actual pressure difference was considerable, the conventional tyres being inflated to 90psi, while the flotation tyres were at just 32psi. The tyres on the Claas Arion 540 were kept at the same pressures for both tests. As with the ploughing trial, a load sensor monitored the draught force and in this case showed that the power needed to pull the trailer on flotation tyres was approximately half that for the standard tyre version. Wheel slip was measured by marking a start point and then counting ten wheel revolutions and marking the finish point. There was a considerable difference in the distance travelled, the flotation tyres having travelled several metres further indicating a much lower amount of wheel slip.

Soil compaction tests were carried out on the wheelings left by the two trailers so that a comparison could be made, and even without the scientific equipment the difference between the depth of the wheelings was obvious. A soil probe was pressed into the soil in several places in each of the wheelings and measurements taken. What was particularly interesting was that not only was the soil compacted far more under the conventional tyres, but as the probe was pressed deeper into the ground it showed that peak compaction was at about 35cms below the surface, below the level at which it could simply be “ploughed out.” This meant that costly subsoiling operations would be required in order to remove the compaction, so not only could the flotation tyres save fuel through the reduced effort needed to pull the load along, but they would also save fuel when cultivations were being carried out as the land would require less working.

One of the main benefits of the day was that attendees were able to see for themselves in a practical demonstration the benefits of the latest technology. The higher specification tractor tyres and the flotation type trailer tyres do have considerably higher purchase prices than the more conventional options, but the benefits claimed in terms of possible fuel savings and reduced soil damage were shown to be real, and as a result the purchase price more easily justified.

Ploughing across the ruts created by the trailer tyre tests. The draught sensors had been expected by many to show an increased load when the deeper wheelings from the conventional tyres were encountered, but in practise little difference was seen, because the peak compaction had been caused below the depth at which the plough was able to remove it.

James Craske of HH Craske and Son, Barrards Hall, Hadleigh, Suffolk, who farms 1,800 acres, was interested in the benefits of using higher specification tyres to provide extra draught for ploughing.

Michael Read of MF Read and Sons farms 1,100 acres at Elms Farm, Depden in Suffolk. “The compaction testing was fascinating,” he said. “The reduced draught needed to pull the trailer and the reduced soil damage was a real eye opener and the obvious benefits in terms of fuel saving while carrying out the tasks as well as the potential savings during cultivations on the land later were very interesting. It was a very worthwhile day. We read about the benefits and the theory but seeing it all for yourself is believing.”