A French study has demonstrated the effectiveness of improved flexion (IF) tires at reducing soil compaction compared to a set of tread tracks. 
The study, organized by the French National Research Institute of Science and Technology for Environment and Agriculture (IRSTEA), measured the soil compaction rates on a 3.5 hectare plot of farmland after a loaded combine harvester fitted with three different mobility options – a set of Michelin CerexBib 800mm IF tires, a set of CerexBib 900mm IF tires and a set of three 760mm roller tread tracks – passed over it.
On soft ground, the combine harvester fitted with the three small tread tracks increased the hardness of the ground by 55% compared to the control area. When fitted with IF 900mm tires inflated to 1.4 bar, the harvester increased ground hardness by only 46%, or 9% less than the tracked machine.
“The objective of the study was to measure the difference in compaction between the two technologies,” commented Mike Lawton, commercial director of Groupe Michelin’s agriculture division. “Farmers and contractors are under increasing pressure to increase crop yields year after year and so they want to make sure they are using a mobility solution that offers the lowest compaction rates.”
On hard ground, tests showed the tracks exerted uneven pressure on the ground, with peaks reaching levels up to two times higher than those obtained with IF tires, which distributed the load evenly over its entire footprint.
The combine harvester fitted with 900mm IF tires, inflated to 1.4 bar, evenly spread the pressure exerted on the ground, calculated at slightly over 4 bar. With tread tracks, the combine harvester exerted uneven pressure on the ground, with peaks (corresponding to the impact of the rollers) approaching 9 bar, or twice the pressure exerted by the tires.
“The study concluded that the tread’s uneven load distribution and the extra pressure on the ground, compared to the IF tires, did not give it an advantage in terms of soil compaction,” Lawton added.
Michelin says the key to achieving this performance is its patented Ultraflex technology; it says the CerexBib is the only commercially available harvester tire that can work at a pressure of less than 2 bar. This is around 30% less than conventional tires. (Tyres & Accessories)
