Which agricultural tyre is most suitable for road transport?

An agricultural lug tyre is designed to provide maximum efficiency in the fields, but in practice tends to be used more and more on the road for long trips between the fields and the farm or the cooperative. On average we frequently see 65% use in the fields for 35% use on the road.
Whilst their efficiency in the fields is obvious, are you certain to have the best suited agricultural tyres for transportation by road?
Tyres are not all the same and if they have not been designed taking into account frequent use on the road, they will wear very rapidly in contact with the asphalt which is highly abrasive for the rubber.

In this article we look at the characteristics which make an agricultural lug tyre a good piece of equipment for use on the road.

1. To begin with, look for a multipurpose tyre

Tyres that have blocks rather than lugs on their tread are obviously more efficient on the road. However, these can be used solely for 100% road use, because in the fields they will be much less efficient than a tyre with lugs, which are essential to obtain good traction on loose soil and in wet conditions.

It is therefore a matter of choosing the most versatile model of lug tyre to manage the long distances by road.
This tyre must have good traction capacity and good road driving characteristics to obtain the best road/field compromise.

To make the right choice, several criteria must be taken into account, such as:

• The quality of the rubber for resistance to wear

• The volume of rubber in the tread

• The tyre’s resistance to speed and load related strain

• A sophisticated tread profile: number of lugs, their positioning and angles.

2. An agricultural tyre with more rubber, or rubber that is more resistant to wear

In the fields, the entire length and width of each lug grips the soft earth, which ensures good traction capacity. On the road, however, the lugs are simply laid flat on the surface and only the outer part of the lug is used in transferring power to the ground.

If the layout of your farm means that you spend a lot of time on the road, you must give priority to a tyre which is made of thicker rubber that is more resistant to wear.

What impact does the road surface have on tyre rubber?

The surface of the road is made up of several different highly abrasive materials such as pieces of crushed rock and gravel.
These different aggregates move up to the surface of the asphalt forming sharp, rough irregularities, causing rapid wear to an agricultural tyre.
For this reason, it’s best to opt for a tyre whose rubber has been specially engineered to resist wear.

The impact of badly maintained roads on your tyres

The abrasiveness of the ground is not the only cause of premature wear to your agricultural tyres. The condition of the road surface is another factor that should not be neglected.

Certain poorly maintained roads, such as secondary country roads, may damage your tyre rapidly. These roads may be misshapen or have bumps or potholes and this rubs off small particles of rubber from the lugs. The tyres’ wear life will be rapidly reduced.

It is therefore important to choose a tyre model that can resist frequent knocks and impacts during regular travel on damaged roads.

The effect of speed on tyre wear

When you drive on a dry asphalt road, only the outer edge of the tyre lug is solicited.

Tyre wear will be linked directly to your speed:

• If you drive quite slowly: there will be much less wear, because adherence will be good and the slip rate will remain extremely low.
  

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• On the other hand, if you drive faster, the tyre will wear rapidly, because the temperature of the rubber increases with speed, which makes it more supple and more sensitive to abrasion.
  

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• Furthermore, sharp braking or a rough style of driving will have a major impact on rubber wear.
  

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It is therefore advisable to moderate your speed or the ‘sporty’ driving style in order to keep your agricultural tyres in good condition. This also improves your braking safety.

Whatever the case, your choice must be oriented towards a tyre model which boasts superior quality rubber in order to limit this type of abrasion despite speed.

3. An agricultural tyre with a resistant casing

Certain criteria must be respected to ensure your next tyre is resistant to wear during road use and efficient in the fields on loose soil. One of the most important of these criteria is the quality and resistance of the casing, taking account of the manufacturing process and its capacity to withstand pressure and resist load.

The production quality of the casing

Each manufacturer uses different materials in the production of its products.

The internal (bead, ply, sidewalls) and external (tread design, volume of rubber…) construction elements are specific to each manufacturer.

Certain brands save on materials to produce low-cost tyres, whereas other recognised manufacturers, like Bridgestone, use superior quality materials stemming from many years of research and development.

The capacity to withstand pressure

When you choose your agricultural tyre, make sure that the casing has the capacity to withstand a high inflation pressure.

A tyre whose casing allows you to drive continuously at a higher inflation pressure than average (between 2 and 2.4 bar is forcibly more resistant and better designed.

For long distances by road, carrying a load, the tyre must be able to cope with a higher inflation pressure. It must be designed with a robust tread belt, a reinforced sidewall and a more solid bead.

More resistance to load

Each agricultural tyre is designed to bear a defined maximum load. Failure to comply with the load index recommended by the manufacturer could lead to premature damage to your tyre, because when it flattens onto the ground, there will be too much deflection in the sidewall, which also has a negative impact on the internal structure of the casing.

You must therefore choose a tyre built around an ultra-resistant casing which can carry a bonus load.

If a pressure of more than 2.5 bar is authorised for use with an exceptional bonus load at low speed, this means that the manufacturer is sure of the quality and resistance of its product.

4. An agricultural tyre with good stability and less vibrations

The tyre is the only element in contact with the ground on the road. The stability of the agricultural vehicle will therefore depend on the design and resistance of this tyre.

During the development of a tyre, the manufacturer defines the position, the number and the form of the lugs to obtain a perfect compromise between road and fields.

• On the road, the lugs must continue to connect with the ground without creating vibration and while maintaining perfect lateral stability.
• In the fields, on the other hand, the length and form of the lugs must ensure a perfect grip on the ground to optimise tractive force.

This capacity to obtain the best in both situations is the fruit of long research and development studies and tests to obtain the ideal compromise.

Good braking capacity when cornering

The brake force is applied directly to the front axle, crushing the front tyres during an emergency stop or the sidewalls when braking going round a bend.

If the tyres are not at the right inflation pressure, if there are weaknesses in the casing or if the beads are not perfectly connected to the rim, there is a risk of the tyre coming off the rim or loss of pressure causing an immediate loss of control of the vehicle.

When you replace your agricultural tyres, take the time to check the manufacturer data on the reliability and solidity of the casing, the bead technology and the resistance of the sidewalls, which will all be essential in the event of sudden braking during transportation by road.

A reduction of vibrations

Several factors may cause vibrations when driving, and in certain cases this can come from the tyres.
Beyond geometry problems or mounting errors, there is a possibility of vibration linked to the tyre’s design.

This could be due to the number of lugs, their form, to the flexibility of the tyre or its pressure capacity.

5. The VX-TRACTOR tyre is highly versatile and performs well on the road and in the fields

It has been designed specifically for farmers with a multipurpose use of their tractors. It allows you to obtain superior traction in the fields at a low inflation pressure and offers indisputable road handling capacities at a high inflation pressure: stability, cornering, and very high resistance to wear.
By opting for a high-tech tyre, you obtain many advantages.

A robust casing which increases the load capacity during transport by road and in the fields

The VX-TRACTOR tyre has a solid casing engineered to reduce internal stress and optimise its capacity to carry heavy loads.

It can withstand an inflation pressure of 3 bar with a bonus load at low speed. For certain sizes (e.g.: 520/70 R38) it has two additional tread plies compared to standard market tyres, which is to say 6 plies in total to ensure perfect driving stability, as well as 3 casing plies for optimal resistance to pressure and load.

Its pressure range goes from 0.6 bar to 2.4 for normal use, making it perfectly adapted to each type of use.

A tread that is optimised for the road

Thanks to its superior quality, reinforced tread which improves resistance and minimises the effects of erosion and rubbing during use on hard ground, the VX-TRACTOR tyre handles well on the road, with a minimum amount of vibrations and perfect handling in the bends thanks to its S-Line bead which secures the tyre-rim connection.

The Involute lug design used in Bridgestone’s most sophisticated tyres offers an excellent traction capacity and minimises the soil disturbance effect caused by classical lugs. This allows you to increase speed on the road and your productivity when working in the fields while limiting slip and soil compaction.

Up to 20% more rubber for a longer lifespan

One of the greatest attributes of the VX-TRACTOR tyre is its resistance to wear and to cuts.

It was effectively designed using superior quality materials and using a rubber compound containing plant-based oil, which is much more resistant to wear than other models on the market.

In addition to this major innovation, its lugs are longer and contain up to 20% more rubber than its competitors, which means that it can easily withstand intensive use on the road and has a longer wear life.

To learn more about ways to increase your farm’s productivity, bridgestone-agriculture has created a comprehensive eBook on the topic which is available for you to download for free:

Bridgestone-agriculture Blog is written and administered by tractor tyre experts who are available to provide you with advice on agricultural tyres. They will help you to maximise your productivity with information on all things relating to tyres: inexpensive tractor tyres, technical data for agricultural tyres, solutions for avoiding soil compaction, sprayer tyre pressure, why and how to ballast your tractor tyres, when to use dual-wheels, the mechanical causes for abnormal wear, discounted agricultural tyres, etc.

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