The Lalich family have found success with Pottinger for their dairy farm and contracting business at Ngarua, near Morrinsville, where a manager looks after the farm, leaving father Trevor, and son Daniel free for the contracting work.
This shows the effect of tyre size and inflation pressure on resultant ground pressure and hence the extent to which the soil may be damaged, a spokesman says.
“For the maintenance of soil fertility and performance, vehicle weight must be kept as low as possible and the largest-possible tyres (diameter-wise) are shown for each model.” Of course, this helps distribute the load evenly, while the larger ‘contact patch’ helps retain soil structure.
For example, on a Pottinger Torro Combiline with an axle load of 10 tonnes and fitted with 800/45 R26.5 tyres inflated to 1.6 bar for road use, the resultant ground pressure in the paddock would be 1.66kg/cm². When shod with smaller 710/45 R22.5 tyres, these figures increase to 2.6 bar pressure on the road and 2.2kg/cm² in the paddock.
Drawing on data provided by the Southwest Falia Agricultural College in Soest, Germany, the company also notes that creating a 1cm-deep wheel-mark in the paddock can consume up to 10% more diesel, due to the increased rolling resistance.
Pottinger claims compaction damage can even result in fertiliser costs rising by up to 20%.
Other benefits include a smoother ride for the operator and the machine, with the latter suffering less strain and metal fatigue when optioned with the correct tyres inflated to the ideal pressure.
The manufacturer warns that for safety reasons the tyres should not be over-sized, as this might adversely affect the efficiency of the brakes and handling while cornering.