## 4 Discussion
The radial tire responded to the increase in inflation pressure differently than the bias-ply tire. Reducing the inflation pressure resulted in an increase in the tire footprint and cross-section area. This trend was visible for both vertical load levels. At the same time, it was found that the inflation pressure had a greater impact on the changes in the linear dimensions of the footprint (especially the width). Such relationships seem to be reflected in work [25], in which a radial tire was tested at normal pressure (70 kPa), underinflated, and overinflated. It has been shown that reducing the pressure allows for a larger contact surface and lower contact pressures. A similar observation was presented in work [50], where the influence of inflation pressure on the value of tire penetration in the soil was analyzed, and in each case, the best operating conditions concerned the lowest inflation pressure. Works [17; 51] also showed that a radial tire responds better to lowering the inflation pressure by having a larger contact surface with the ground. In analyzing the influence of vertical load, it was found that in the case of a bias-ply tire, it had an impact on all analyzed parameters. In each case, an increase in parameter values was observed as a result of the increase in vertical load, with the largest changes observed in the tire footprint and cross-section area and the smallest changes in the footprint width. This tendency is similar to the results presented in the literature--for example, in works [3; 17; 31], it was shown that an increase in vertical load results in an increase in rut parameters (especially the vertical depth). In turn, for a radial tire, a significant impact of the vertical load was found only on the size of the footprint surface and the cross-section of the tire and on the footprint length and width. However, there was no effect on the footprint depth, which may indicate the better adaptation of the tire to the ground as a result of vertical load changes (the footprint area increased so much that the tire had a larger contact area; so, there was no tendency to sink the tire into the soil). This tendency seems to be consistent with the results obtained in [2; 32]. It is very important that the practical aspects of tire research be taken into account in addition to the scientific aspects. In the case of analyzing the impact of wheels on the soil, the main practical aspect is the necessity to reduce compaction by indicating such factor values that result in the greatest width of the rut length and the largest contact area of the wheels with the ground. This results in the least deep impact of the wheels on the soil, and as a result, better soil aeration, better moisture conditions, and lower mechanical resistance to the roots of the plants. It means that properly selected tire operating conditions can give higher yields and lower energy consumption via agricultural equipment. Many economic benefits can be achieved when farmers control operational parameters. First of all, by selecting the tire pressure and vertical load, you can ensure the optimal adjustment of the tires to the ground and, as a result, reduce pressure and compaction. This, in turn, allows for lower mechanical resistance that the soil will pose to agricultural machinery elements. This, in turn, has a positive impact on energy use (reduction in fuel consumption). These changes become visible especially after a longer time--after a larger number of treatments. Practical activities based on obtained results can be integrated into existing agricultural work management systems. This applies especially to tire inflation pressure management systems because this parameter can be changed quite quickly even while driving a tractor. Combined with the work management system, this can operate continuously, adapting the pumping pressure to the current operating conditions of the tractor, thus ensuring less soil compaction.