Tyre Selector

Crop Treatment: should you use bias or radial tyres?

The crop treatment period can be very complicated because of the weather. It's often in wet conditions that you're going to apply crop treatments or fertiliser, which can have a major impact on soil compaction.Soil compaction arises when the soil in the field is loaded beyond its stability level when being driven on, i.e. if the pressure of the tyres on the soil is greater than the counter pressure (the counter-tension of the soil). The proportion of solid substances in the soil structure therefore increases and the proportion of pores.

The best way to limit this is to work at low pressure. In fact, it's recommended that you do this every time you work in the field, even outside the crop treatment period and even in dry conditions. When harvesting, for example, the risk of compaction is also high because the machinery used is heavier and compacts the soil.

But it's when you're working in wet conditions that the risk of compaction is increased. Fortunately, the right choice of tyre technology can reduce this phenomenon.

Michelin invented radial technology in 1946. Why was this a major innovation? Because the principle of the radial is that the sidewalls are separated from the crown. So when you deflate a radial tyre, the sidewalls flatten out. And because the center of the tyre is separated from the sidewalls, the area of contact with the ground is extended, taking on a rectangular shape.

On a bias tyre, the crown and sidewalls are linked, which gives a domed shape. When the tyre is deflated, this affects the tread as much as the sidewalls, which means that the shape of the contact patch with the ground is elliptical and therefore smaller than on a radial.

The advantage of radial tyres is that by lowering the pressure, the tyre's footprint on the ground is longer , and as the load is spread over a larger surface area, it is less per square centimetre.

There are two aspects to tyre life: impact resistance and endurance.

A bias tyre is more resistant to impacts because it is made up of several carcasses. On the other hand, it heats up a lot when it is under heavy stress, particularly during the crop treatment phase when the tanks are heavy and the tyres narrow.

A radial tyre, which has only one carcass, deforms less and dissipates more heat, which makes it better in terms of thermal resistance. They are designed to be more durable than bias tyres, because they have a greater surface area in contact with the ground, which means that the load is distributed more evenly and consequently wears more uniformly, resulting in longer life. A bias tyre, which has an elliptical footprint, is subject to local overpressure, which tends to make it wear more quickly.

The three ranges of MICHELIN Ultraflex radial tyres mentioned above are also compatible with the CTIS (Central Tyre Inflation System)^(**). In other words, you can use this system to adjust tyre pressure without leaving the cab of your vehicle, so that it's always at the optimum level for your use.
Optimised tyre pressure means you get all the benefits your tyres are capable of delivering (very low pressure with MICHELIN Ultraflex technology, less soil compaction, better traction) and avoid unnecessary fuel costs.