The performance of agricultural tyres in soft soil conditions

Abstract

In intensive arable farming, more and bigger tyres are having to be used in order to support the ever increasing loads to be transported. In Dutch agriculture, to keep rut formation and subsoil compaction within critical limits, it is assumed that tyre inflation pressure should be reduced to 100 kPa or less. However, it is shown that reducing the inflation pressure leads to an exponential decrease in tyre loading capacity. To compensate for this phenomenon, bigger, i.e. wider tyres, with more loading capacity at these low inflation pressures, are needed. The rate of soil-pressure reduction with depth is slower for wider tyres, which is in principle a disadvantage where subsoil compaction risks are concerned. In practice one may avoid problems by using tyres with dimensions that ensure a sufficiently low level of pressure in the tyre-soil contact area. A low, harmless, level of pressure is then reached in the lower tilth and subsoil. Applying low-ground-pressure (LGP) systems often means that special wheel equipment is needed, such as steered wheels in a tandem configuration, 4-wheel drive, etc.