Key explanations on load and agricultural tyre ballasting

Your tractor tyres are designed to bear heavy loads, the weight of your tractor of course, but also your tooling, they are solid and highly resistant tyres. However, you know very well that this doesn’t mean you can mount any size of tooling or add mass indefinitely, the limits in terms of load and ballast are entirely linked to your tyre model. These limits are essential and must be respected, for your safety to begin with, as well as to make your equipment last over time, to preserve your soil and make savings by having the best settings possible for your trailer.

Here is what you need to know to manage the load and find the best settings to optimise your productivity:

1. Compensate for tractor mass by increasing tyre pressure

Load and pressure are directly linked: the mass of the tractor, with its implements, crushes your tyres directly up to a certain limit, it’s the quantity of air contained in them (thus the pressure) which makes it possible to compensate for this crushing effect.

If you transport heavy loads, you must increase your tyre pressure to bear these loads. However, if there is not much air in the tyre due to its size, for example, it will not be able to bear a heavy weight. There is a direct relationship between the volume of air contained in a tyre and its pressure.

To define the right pressure, use weighing equipment for the front and rear axles. This will allow you to check the actual weight borne by your tyres and check that this effectively corresponds with the load index indicated on the tyres.

Never exceed this index if you wish to avoid damaging your tyres rapidly or risk bursting a tyre as a result of overheating when driving if you go well beyond the limits.

But bear in mind that there are some disadvantages to increasing tyre pressure. If you are working on loose ground with overinflated tyres, there may be very negative consequences:

• Excessive soil compaction
• Increase in slippage rate
• Increase in rolling resistance and therefore fuel consumption
• Formation of ruts

Big load transfer to the rear axle

2. You can increase the load by using wide tyres with a bigger volume of air

More than the pressure, it’s the volume of air in the tyres which matters if you wish to transport the heaviest loads, pull wider implements, or full trailers during harvesting, for example.

When changing your tyres, you can therefore take the opportunity to increase the rims and choose a wider set of tyres with a higher volume of air. By opting for bigger tyres, you will have more air to bear the mass without being obliged to increase the inflation pressure too much.

For example, for a speed of 30 km/h:

• With 580/70 R42 tyres with a pressure of 1.6 bar, you will have a load capacity of 4,890 kgs.

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• If you use a tyre with a higher volume of air but the same rolling circumference, i.e. 710/70 R38 IF Maxi Traction, we obtain a load capacity of 6,555 kgs at 1.6 bar pressure.

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Increase tyre size
to pull bigger implements

3. Why use metal ballasting?

An agricultural vehicle’s traction capacity is directly linked to its weight and to the balanced distribution of load transfer to both axles. For work requiring maximum traction, such as tilling, ballasting your tractor is strongly recommended, especially if it is light, in order to increase its traction capacity by rebalancing the load between the rear and front axles.

To optimise the driving capacity of your trailer, you can apply the following rule: the overall mass must not be lower than 50 kg per hp.

Example: if we take a 190 hp tractor, the mass necessary to ensure good traction will be a minimum of 9,500 kg minimum (190 x 50 = 9,500 kg).

What are the advantages of using cast iron ballast weights?

Metal ballasting is relatively simple and quick to set in place if you have adequate lifting equipment. Like with all the other ballasting systems, there are numerous benefits:

• Improved adherence to the ground leading to better traction
• Reduction in slippage rate
• Optimisation of work efficiency (reduced working time)
• Less wear to the lugs (longer tyre lifespan)

To adapt the load distribution between the tractor’s front and rear axles, the best technique is to use metal weights.

You can increase or reduce the number of weights depending on the weight of your implements to optimise adherence to the ground.

Front metal ballast weights

Basic rules when using metal weights

In detail, metal ballasting consists in installing metal weights (often made of cast iron) on the tractor or its wheels (hubs or axles). Due to the heavy weights involved, you will require lifting tools to carry out the operation successfully.

For optimal ballasting, a few essential basic rules must be followed:

• Too much weight on the rear axle hinders the handling capacity of your tractor. The front axle will tend to lift up more easily leading to a loss of grip at the front and therefore difficulties in terms of steering to control your trailer, especially in wet conditions. In addition, the excessive load on your rear tyres leads to greater rolling resistance and excess slippage at the rear, with consequences above all on your fuel consumption.
• Too much weight on the front axle means that you will lose traction efficiency in the rear tyres, increase wear to the front tyres due to slippage and face difficulties pulling the combination vehicle.
• For a tractor with four-wheel drive, the correct weight distribution should be a maximum of 35 to 40% at the front and 60 to 65% at the rear.
• You must ensure that the overall mass: weight of the tractor plus implements, plus additional weights does not exceed the load index indicated on the tyres’ sidewall.

Good load distribution between my tractor tyres