VF (Very High Flexion) tyres are the latest generation of agricultural tyres that offer more load capacity with lower operating pressure. But what are the practical benefits? In this expert guest blog, Product Manager Tero Saari from one of our prestigious partners Nokian Tyres gives a different perspective on VF tyres.
In the farming business, the choice of tyres is just one factor. But VF tyres can be one of the small streams that make up a river of productivity. Investing in a quality tyre is therefore a technological investment that brings benefits on many levels, including:
- working efficiency
- fuel savings
- faster road transitions
- keeping the soil productive
- long tyre life
By choosing the right tyre for the right need, you can help build a sustainable agricultural sector that ultimately benefits everyone. In this article, I explain in more detail what VF tyres are all about and the benefits they offer.
VF tyres – What are they and what are they not?
When talking about VF tyres, it is important to remember that VF is not a "technology" but a standard. The European Tire and Rim Technical Organisation (ETRTO) has agreed on a set of common rules and practices so that, for example, the load capacity of a VF tyre is always calculated in a comparable way, regardless of the manufacturer.
The load capacity per unit of pressure is therefore a key element of the VF standard and is typically 30–40% higher than for a tyre based on the conventional agricultural radial tyre standard. However, the standard does not specify how this should be implemented technologically, so each manufacturer develops tyres to the standard according to their own criteria.
The VF standard allows a wider range of tyre pressures. In practice, the lower operating pressure allows the tyre to compress efficiently to maximise ground contact, resulting in the machine’s weight being distributed over a larger contact area, keeping the soil fluffier and improving traction.
However, the standard does not make low-pressure operation mandatory, and when driving on the road, it is still worth increasing the pressure to improve stability and further reduce rolling resistance. Still, the VF tyre can also withstand transitional driving at lower pressures than a typical agricultural radial tyre.
Controlled stretching for improved soil contact area
In its standard, ETRTO defines a sizing range for the nominal size of tractor traction tyres, with an upper limit on the diameter and width of the tyre. This means that even tyres of the same nominal size can be of different dimension in width and diameter within certain limits.
As the large size provides more contact area, the most advanced VF tyres are designed closer to the upper limit of the size range. Stretching while use is controlled by advanced structural and material technology enabled by state-of-the-art manufacturing processes.
The right agricultural tyre reduces rolling resistance and improves fuel consumption
With typical agricultural tyres, lower tyre pressure means greater tyre deformation which adds to higher rolling resistance, heat build-up and tyre wear. With advanced VF tyres, these adverse effects can be avoided.
The effect of rolling resistance on fuel consumption is not marginal: for example, a 38% increase in rolling resistance increases fuel consumption by 5%. With a fairly typical consumption of 25 litres per hour, this equals 1.25 litres per hour. In other words, it takes 22.5 litres from a 450-litre tank to overcome the rolling resistance.
The design of a tyre, i.e. the choice of material, shape and structure, has a major influence on the amount of harmful thermal expansion that occurs. A low-pressure tyre requires specific tyre technology know-how to control energy loss and its negative effects. In this way, tyre deformation is carried out with high efficiency and its benefits are achieved with a minimum of inconvenience.
The new Nokian Tyres Soil King VF tyre has an exceptionally low rolling resistance thanks to the advanced Flexforce technology.
Discover the Nokian Tyres Soil King VF tyre
More yield, less energy loss
The lower surface pressure of VF tyres significantly reduces the compaction, which weakens soil structure. In other words, soil porosity is better maintained for plant vitality when the soil is not compacted because the space needed for water, nutrients and plant roots is in the soil pores.
Ground pressure also causes topsoil damage and resistive force as the tyre is forced to push the topsoil in front of it. The resistive effect of pushing is equivalent to driving uphill all the time. 1 cm of soil compaction increases energy loss by 10%. Therefore, lower surface pressure on soft ground also has the effect of reducing energy loss.
Better tractor handling in road transport.
Drivability is an important part of overall performance. However, it is well known that lower tyre pressure usually reduces tyre stability. For example, driving a tractor with large implements on narrow country roads can be downright scary when reduced visibility is combined with difficulty staying in lane. Then you must slow down, wasting time on unproductive work.
Read user experiences with VF tyres from Nokian Tyres website.
I have been involved in the development of the Nokian Tyres Soil King VF tyre from the very beginning, with the aim of minimizing the negative effects of low tyre pressure on drivability. That is why it has been great to hear from end users how the tractor has maintained good drivability even with less than 1 bar of tyre pressure and heavy seed drills in front and behind.
Writer
Tero Saari
Senior Product Manager, Nokian Tyres
Questions about VF tyres?
Contact: tero.saari@nokiantyres.com
