The calculation of the load transfer to your agricultural tyres is absolutely vital to ensure that your equipment performs well and to preserve soil quality. Poor management of load and too much load transfer to the axles can cause major problems: soil compaction, slippage, premature tyre wear and damage.
For farmers, too much load not only compromises the efficiency of operations, it also leads to additional expenses such as extra fuel costs, rapid wear to your equipment and more frequent replacement of your tyres.
This article explains how to calculate the load carried by your tyres, the importance of the load transfer and how to take it into account when using your implements. We will also look at practical solutions, including the use of low pressure tyres, to help you optimise settings and improve the profitability of your farm. Let’s move from theory to practice to get the most from your equipment.
There are multiple possible consequences if you overload the structure of your tyres, and this may prove costly in the long run.
An excessive load makes it necessary to increase the pressure in your tyres to compensate for the extra weight. If the increase in pressure is not enough, this leads to an excessive distortion of the sidewalls and casing of the tyre.
The tyre components are pushed beyond their limits which can lead to structural weaknesses or even total rupture.
Too much load or an unevenly distributed load cause premature tyre wear. Crushed by the weight, the lugs wear more rapidly, the sidewalls become misshapen and the casing weakens.
Too much ballast or imbalanced ballast can worsen the problems. This creates additional strain on the tyres, leading to premature wear and increasing the risk of distortion.
In addition, incorrect balance between the ballast and the attachment can lead to variations in load transfer which also accelerate damage to the tyres.
In addition, overloading tyres has direct consequences on soil quality and tractor performance in the fields.
An overloaded tyre exerts too much pressure on the soil, compacting it and reducing its porosity. Plant roots find it difficult to penetrate, which limits their development and affects your yield.
A heavy load means that you have to increase pressure to compensate, which limits the size of the tyre footprint and grip, thus reducing your tractor’s traction capacity, especially in wet conditions or on sloping land.
Too much load or unsuitable pressure settings increase rolling resistance, create deep ruts and encourage wheel slip.
This accelerates tyre wear and increases the production costs linked to frequent replacement of your equipment.
Calculating the load borne by the tyres of an agricultural vehicle consists in determining the vertical force applied to each of them. This force takes several factors into account:
To calculate the load borne by your tyres and define the right pressure, several tools are available to you:
The load can be calculated simply by adding up the weight of the vehicle, the implements, the ballast and the payload, then spreading this total load over the different axles depending on their position.
When you have found all the weight related information in the manufacturer data and you have taken your measurements, you can make the calculation as follows:
Like for the calculation with weighing equipment, you can check that the end weight obtained is in line with the load index indicated on each tyre.
You will then be able to adjust pressure based on the load and the intended travel speed.
Tyre pressure must be adapted to the actual load, to the working conditions and to travel speed by road. Insufficient pressure compared to the load leads to an excessive distortion of the tyre and premature wear, whereas too much pressure increases rolling resistance and encourages soil compaction.
Load transfer is what occurs physically when an agricultural vehicle is equipped with implements or additional weights.
It consists in the redistribution of the weight of these elements between the different tractor axles. In other words, the load transfer describes how the weight of an implement, a tool or a payload or ballast influences the pressure exerted on each tyre.
Good management of the load transfer is essential to optimise tractor performance. By spreading the weight in a balanced way, it is possible:
For a practical illustration of the calculation of the load transfer, here is an example corresponding to the preceding formula:
FRONT load = 1,200 kg × (1300 + 2900) + 3,860 kg = 5,598 kg
2900
REAR load = 3,500 kg × (2700 + 2900) + 5,790 kg = 12,548 kg
2900
Front: 600/70 R 30 = 1.2 bar at 40 km/h
or 1.0 bar at 10 km/h
Rear: 710/70 R 42 = 1.6 bar at 40 km/h
or 1.4 bar at 20 km/h
The choice of tyres is an essential step in reducing the impact of the load to the ground. VF (Very High Flexion) tyres represent a significant breakthrough in this domain.
Thanks to their reinforced internal structure, VF VT-TRACTOR tyres can carry 40% more load compared to standard tyres, while maintaining a low inflation pressure. This feature makes it possible:
To optimise the capacities of your VF tyres, especially if you make a lot of trips by road and cover long distances, you can use a central tyre inflation system which will be particularly useful.
This allows you to adapt pressure depending on the load, but also based on travel speed on the road.
In addition to adjusting pressure based on your load, as advised by your tyre manufacturer, you should adapt to your environment and slightly increase or decrease pressure so that your settings correspond perfectly to your specific situation.
Optimal management of load transfer to agricultural tyres is essential if you wish to preserve your tyres and your soil. Using suitable tyres, such as the VT-TRACTOR tyre, makes it possible to work with more load while reducing compaction, increasing traction and decreasing operating costs.
By adjusting pressure correctly based on the load and adopting targeted agronomic practices, you will be able to get the most from your equipment. Putting theory into practice in the management of load transfer is a worthwhile investment, from both an economic and an environmental standpoint.
The Bridgestone-agriculture.eu blog is written and administered by tractor tyre experts who are available to provide you with the advice that you need about your farming tyres. They will help you to maximise your productivity with information on all things relating to tyres: inexpensive tractor tyres - technical data for farming tyres - advice on farming tyre pressure - solution to avoid soil compaction - sprayer tyre pressure - Why and how to ballast your tractor tyres - when to use twin wheels - the mechanical causes of abnormal wear - cheap agricultural tyres - etc.
To take it a step further and increase the profitability of your farm, the tractor tyre experts has prepared a free, highly detailed, ebook which explains the essential role of farming tyres on your productivity.
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