APOLLO TYRES / VREDESTEIN TYRES Vredestein Flotation Optimall VF 750/60R30.5

The correlation between the contact area, the contact area pressure and the resulting ground pressure becomes visible through the generated track depth. As the track depth increases, so does the risk of compaction and the need for more intensive tillage to loosen and level the tracks. The Vrede­stein Flotation Optimall VF 750/60R30.5 187D produced the lowest track depths in all three infla­tion pressures in the test conducted. On average across all infla­tion pressure variants, its track depth was 24 % lower than that of the runner-up of the VF competitors.

Depending on the design and construction, the different tyres behave differently in the track and dissipate the force in different directions into the ground. Such design-related differences are shown in the test by different penetration resistances in the shoulder or in the center of the tyre track. Increasing penetration resistance is measured in the shoulder of the tyre track as the tyre’s infla­tion pressure decreases. Compared to the other tested tyres, the Vrede­stein Flotation Optimall VF 750/60R30.5 187D is in the lower to medium range. In the center of the tyre track, the Vrede­stein Flotation Optimall VF 750/60R30.5 187D tends to have higher values, but these are still well below the measured penetration resistances of VF Premium reference tyres B.

The measured fuel consumptions are subject to a strong scattering, so that some of the obtained results can only be evaluated as tendencies. In the test conducted, the Vrede­stein Flotation Optimall VF 750/60R30.5 187D had the lowest fuel consumption in the 1.7 bar infla­tion pressure variant when compared with the other VF tyres.

The fuel consumption determined for the Vrede­stein Flotation Optimall VF 750/60R30.5 187D in this tyre pressure variant was 14.9 l/hr and around 1 l/h (VF reference tyre B-Premium) to 3 l/h (VF reference tyre C-Budget) lower than for the other VF tyres tested.

Table 1: Overview of results

* Der DLG test framework provides the following options in its evaluation schemes:  
■ ■ ■ or better = meets, exceeds or clearly exceeds the specified DLG standard, ■ ■  = meetsthe legal requirements for marketability,  ■ =failed

The aim of testing agricultural trailer tyres in the DLG Testing Module “Resources Protection” is to examine agricultural trailer tyres in terms of their effect on the soil and fuel consumption during field use.

For this purpose, the tyres to be tested are mounted on suitable vehicles and driven in field tests under practical operating conditions. For the test drives, a driving speed that is customary in practice during simulated field work is defined and kept constant. The measurements are carried out with three infla­tion pressure settings. The tyre pressures to be set are determined as a function of the actual wheel loads applied during the test via the manufacturer infla­tion pressure tables determined according to the following procedure:

• Maximum (nominal) permissible infla­tion pressure (IP_MAX)
• Medium infla­tion pressure according to manufacturer’s specifications with determined load capacity for 50 km/hr
• Minimum infla­tion pressure according to manufacturer’s specifications with determined load capacity for 10 km/hr (IP_MIN).

To classify the measurement results, comparative tests are carried out in the test with reference tyres available on the market.
The test runs are carried out on suitable agricultural land under equal conditions. The test areas must be sufficiently large, homogeneous, even and well prepared for the work to be simulated. The test areas (soil type, soil texture, vegetation if applicable, field-use history) and test conditions (weather, soil moisture and condition of the test area) are documented. The main technical parameters of the vehicles, that are relevant for the test, are recorded and documented.

The following parameters are determined as essential parameters for the evaluation in the test module “Resources Protection”:

• Soil moisture
• Wheel loads
• Infla­tion pressures
• Actual driving speed
• Driven distance
• Fuel consumption in l/hr
• Wheel contact areas
• Ground pressure during drive over at 10 cm, 20 cm and 40 cm ground depth (Bolling probes)
• Track depth after passing
• Penetration resistance after passing

Ground pressure

While passing, the ground pressure was mea­sured in the test using Bolling tubes.

The soil pressure and its propagation are described in the literature as isobars. The decrease of soil pressure in depth is significantly influenced by the contact area. The pressure under the track in the soil decreases with a higher depth. It is higher for the non-VF standard tyre than for the VF tyres in all test variants. At 10 cm soil depth, the pressure generated by driving over is very closely correlated with the tyre infla­tion pressure. In the deeper measurement zones (20 cm and 40 cm), the effect of the different wheel contact areas becomes apparent. The larger the wheel contact area, the lower the measured pressure at depth. At 40 cm soil depth, the VF tyres generate the lowest pressure at low infla­tion pressure due to the resulting larger contact area. At the high tyre pressures of 3.2 bar in the test, the VF tyres from the premium segment differ only slightly in the generated ground pressure at all three ground depths. This high tyre pressure was not approved for the reference tyre from the budget range, and the variant had to be driven with 2.8 bar. At medium infla­tion pressure (1.7 bar) and at low infla­tion pressure (1.0 bar), the VF tyre from the budget range tends to generate higher ground pressures than the VF tyres from the premium range at all ground depths. Within the VF Premium range, the tested tyres differ only slightly from each other at 20 cm soil depth and higher infla­tion pressures.

At low infla­tion pressure, the Vrede­stein Flotation Optimall VF 750/60R30.5 187D proves 15 % to 20 % lower ground pressure at 20 cm soil depth than the other VF tyres tested. At 40 cm soil depth, the Vrede­stein Flotation Optimall VF 750/60R30.5 187D at 1.0 bar infla­tion pressure has the lowest value of 0.12 bar ground pressure in the premium VF tyre range and across all tyre variants used in the test conducted. The generated ground pressure was 50 % lower compared to the budget VF tyre (0.12 bar vs. 0.24 bar) and 25 % to 30 % lower compared to the VF tyres from the premium segment (0.12 bar vs. 0.16 bar and 0.18 bar). These low values close to zero clearly show the potential of VF technology. Causing a soil pressure of only 0.12 bar at a depth of 40 cm with a wheel load of 7,100 kg represents a major step forward in soil preservation. Figure 6 shows the individual results.

Track depth

The relationship between the contact area, the contact area pressure and the resulting soil pressure can be seen in the track depth. As the track depth increases, so does the risk of compac­tion and the need for more intensive tillage to loosen and level the tracks. Figure 7 shows the track depths measured in the test under the praxis conditions.

The Vrede­stein Flotation Optimall VF 750/60R30.5 187D proves the lowest track depths in all three infla­tion pressure variants in the test conducted. On average across all infla­tion tyre pressure variants, its track depth was 24 % less than that of the runnerup of the VF competitors.