New Tires Boost Yields
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As the tire pressure goes down from 35 psi to 15 psi, the tire flattens and the side walls bulge. The tire may look flat but new tires are designed that way. The tire foot print expands by 4.5 inches which means the load is spread over a larger surface area, resulting in less soil compaction. Traction improves so more field work can be accomplished faster with less fuel and labor.
Less compaction resulted in higher yields. Tire experts tested tires at 35 psi which is over inflated for most new tractor tires and compared that to 28, 20, 12, and even 6 psi on new tires. In every case yields increased. The biggest boost was on going to 6 psi which resulted in 7.5 bushel more corn, however; few tires can tolerate that low of psi. A big yield boost (3.4 bushel) came from lowering tire pressure from 35 psi to 28 psi.
Here are some farm implement tire tips for farmers. First, understand the load/inflation chart that comes with new tires. On VF tires, farmers often over inflate their tires to the old standard of 35-36 psi which ruins the advantages of the VF tires in the field. Soil compaction on a tire is related to tire pressure. The higher the tire pressure, the smaller the tire foot print, and soil compaction increases. This can occur on tractors, combines and even implements, especially grain carts. VF tires can take larger loads, move faster, use less fuel and labor, and reduce soil compaction but all that is negated if the tire is over inflated in the field.
Radial tires on US farms is increasing but it still lags tires made and used in Europe. Tire tread patterns have improved where new tires have a deeper biting edge and higher lateral traction than older tires. Thicker lugs and wider shoulders on tires with overlapping patterns and increased rubber density improve over the road performance. Radial tires in the field tend to be more stable for higher loads with flexible sidewalls and less rolling resistance which gives the farmer a softer ride. They also often look underinflated but they are made that way. On the road those advantages disappear if the tire is inflated to a higher psi. They sway more, are bouncier, and a little less stable.
Ideally, farmers should use a higher tire pressure when transporting their equipment and a lower tire pressure in the field. Some equipment is now coming out with a central tire inflation system (CTIS) which inflates the tires properly from the tractor. When a farmer gets to a field, he pushes a button and the tires deflate to the proper pressure. When he leaves the field, the tires can be reinflated for road speed. It’s expensive costing $20,000 to $30,000 per machine, but the savings can be recovered on large acreage with less compaction, higher yields, lower labor, and fuel costs.
Take time to understand the numbers on your sidewall tires. All tires have a load index and a speed rating. The first number is a load rating followed by a capital letter which is the speed rating. The higher the load rating, the more weight a tire can handle. You need to refer to a index load chart for those numbers. On speed rating, a capital “A” means the tire has a maximum speed of 25 mph, “B” tires can go 31 mph, and “C” can go 40 mph on the road.
Farmers should also know something about the chemistry of the tires they buy. Talk with your tire dealer about getting the right tire for your farm. Tire chemistry is complex and farmers need to get the right balance between abrasion resistance and puncture resistance. Some farmers need to guard against stubble puncture while other farmers in urban areas need more tractor speed on urban roads. All tires and farms are different and the ideal tire is not the same for everyone. Finally, when you buy a new implement, remember to check the tire pressure because often it is over inflated for transport and needs to be lowered for field work.