Maintain Proper Tire Pressure Critical to Avoid Soil Compaction
Proper tire inflation pressure is vitally important to avoid soil compaction and get the maximum out of your tractors, combines, and harvesters. Overinflation may cause loss of traction, excessive compaction, fast wear, high fuel consumption, fewer acres covered, and loss of operator comfort. Underinflation, on the other hand, can cause sidewall damage, a poor ride, tire bead un-seating and fast wear. You should regularly inspect tire pressure to make sure it is still in the optimal range.
Check your tires – if they wear mostly in the center, they are most likely overinflated, while if the sidewall is cracked you may have tires that are regularly underinflated. Surface soil compaction depends on the surface contact stress exerted by the tire. If you compare the surface stress in pounds per square inch (PSI) of a tire inflated to low pressure with one that is inflated to high pressure, you will find that the surface stress is lowest at low inflation pressure – because the footprint is largest. Research performed at Ohio State showed that a tractor with duals inflated to low pressure caused less compaction than a similar tractor with tracks, but when the duals were inflated to high pressure it caused the most compaction. At the same time slippage was high with the high inflation pressure, resulting in fewer acres covered with the same fuel consumption. Unfortunately, tires typically come overinflated from the dealership or when new tires are mounted on rims.
To determine the right inflation pressure, you need three things:Â
- tire load;
- tire size and
- speed of operation.
The fall and spring are two good times to determine proper tire inflation pressure on tractors, combines and harvesters for the harvesting or planting season. With the heaviest load you would be pulling with your tractor or load in your combine, weigh the front and rear axle – for example at the grain elevator. Then determine the maximum speed you will be driving at and write down the tire specs. Size nomenclature can be standard or metric.
An example of standard would be 16.9-30. 16.9 is the width of the tire in inches, while 30 is the diameter of the rim in inches. The dash means bias-ply, which would be replaced by ‘R’ if it was a radial tire.
Most modern tires carry the metric format, an example being 710/40R22.5. In this case the width of the tire is 710mm, the width:sidewall height ratio is 40, the ‘R’ means it is a radial tire, and 22.5 is the diameter of the rim in inches.
When you have determined the tire load (calculated from the axle load) you go to the company tire book or website and determine the proper inflation pressure for your specifications. Use a good tire gauge that is accurate to 1 psi.
