Authored by: Tractor tyre expert | 19 September 2023
Repairing an agricultural tyre may be an economical solution which avoids a costly replacement tyre. However, you need to differentiate between the repair options available and only choose the most suitable solution to make sure that the repairs last over time.
There is no point in makeshift cold repairs on a break in the casing of a tyre, because this type of repair will only last a few days and could lead to an even more expensive accident.
There is a solution for each situation, but in certain cases the only solution is to replace the tyre. The tyre is placed under great stress on a regular basis due to pressure, load or flexion, which means that it needs to be highly resistant.
In this article we look at the different hot and cold repair possibilities depending on each situation.
Cold repairs are often used to fix agricultural tyre punctures.
This technique consists in applying a patch to the damaged area where the puncture is situated.
There is another very effective cold repair solution for very small perforations, consisting in using a mushroom plug to seal up the hole.
You will have to demount the tyre, which allows you to see whether any internal damage has occurred.
Cold repairs are highly effective in specific situations. It is essential to understand in which circumstances they can be carried out successfully.
These can be caused by a branch, a screw, a nail, a metal object, etc.
If you notice the puncture while you are working due to a significant loss of pressure, or if the tyre deflates during the night, you must act rapidly.
In no circumstances must you drive with a flat tyre, or leave the flat tyre on the vehicle for a few days, as this could deform or alter the internal structure of the casing in which case it is not worthwhile trying to make repairs.
This area is thicker than the sidewalls due to several overlapping layers of fibres and rubber.
Thanks to the tread’s robustness, it has a greater resistance to damage and perforation. Because it is less flexible, there is less movement in this area when the tyre is at work, which makes cold vulcanising an option.
Repairs in this solid area generally do not affect the characteristics or wear life of the tyre.
Only punctures situated at the level of the tread can be successfully mended using cold repairs.
The patch used as part of this process is effectively not strong enough to withstand the flexibility needed in the tyre sidewalls, in particular the flexion and deflection linked to driving on rough ground or variations in inflation pressure.
For cold repairs to work, it is vital to target only punctures on the tread, where the structure is more solid and less affected by significant distortions.
It is essential to differentiate between a perforation and a cut. Cold repairs are recommended only in the case of perforation, when the internal structure of the tyre has not undergone any major damage.
On the other hand, a cut which may have sliced through several layers of fibre in the casing over a few centimetres will cause structural weakness. Even the smallest cuts usually require hot vulcanising repairs.
Hot repairs consist in plugging the damage with rubber which then undergoes a hot vulcanisation process so that it blends completely with the existing structure of the tyre.
This method is ideal for more significant damage requiring a very solid repair job.
Hot repairs are the best option for large cuts on the tread or on the tyre sidewalls. The hot vulcanisation process effectively helps maintain suppleness and flexibility and preserves the tyre’s overall performance capacity.
It’s for hot repairs that a good casing is essential. If the materials (nylon and rubber) have bonded perfectly during the manufacturing process, the repairs can go ahead without any problem.
Hot repairs can be carried out on small cracks in the casing at the middle or top of the sidewalls, on the shoulder or even on the tread.
For small hernias that are some distance from the bead, hot repairs can be an effective solution. They make it possible to restructure the damaged area and ensure the integrity of the casing.
The hot repair process guarantees better adherence of the repair rubber and avoids the risk of air leakage or a patch applied during cold repairs coming off.
Vulcanising is an essential step in the hot repair process. It consists in heating the rubber that has been added to 120 degrees to transform its molecular structure.
The heating process makes it possible to bind the rubber’s molecular chains. The modification of the molecular state makes the rubber much more solid although it retains its natural elasticity.
This operation results in the repair rubber and the tyre bonding perfectly, leading to solid, lasting repair work.
You have to accept that some damages cannot be repaired, because in certain cases unsuitable repairs can lead to serious problems with your agricultural tyres, and also with your trailer or trailed implements.
It is essential to recognise these situations in order to avoid repairs that are ineffective or even dangerous for your equipment or your safety.
Too much damage, such as caused by driving with flat tyres, leads to situations in which repairs are no longer an option.
When you drive with a flat tyre for some distance, the internal structure of the tyre will suffer irreparable damage.
Tears at the level of the bead, on the sidewall, but very close to the bead, represent irreparable damages.
The bead zone which contains the bead wire is particularly sensitive and must never be repaired. This type of damage compromises the integrity of the complete structure of the tyre and can lead to serious problems if the tyre is repaired and reused (during inflation for example).
These hernias generally indicate a significant weakness in the internal structure of the tyre, making it dangerous to use.
This type of damage occurs when the internal layers of the tyre come apart, creating a bump or a bulge linked to the loss of internal pressure which manifests itself beneath the rubber on the external surface of the tyre.
In the case of unsuitable cold repairs, there is a risk of the patch coming off after a few days and the tractor being immobilised again in the middle of the fields, which will end up costing you more in breakdown services.
On the other hand, when the tyre shows an increased loss of resistance due to major damages, the risk of an accident linked to unsuitable hot or cold repairs increases considerably.
In certain cases, it would be a shame to be obliged to repair the tractor following an accident as a result of makeshift repairs rather than replacing the tractor tyre, without mentioning your personal safety or that of the other people on the road.
A good repair job can only be done on a quality casing. A casing that is not correctly put together will be very difficult to repair, at least on a long-term basis.
A quality tyre is made up of a blend of materials such as natural rubber, synthetic rubber, carbon black, nylon fibre …
Each of its constituent materials plays a role that a is complementary to the other components.
All these components ensure the robustness necessary for successful hot repairs to be carried out on your agricultural tyre.
Firestone has been one of the market leaders in terms of the manufacture of agricultural tyres for over 100 years, and has developed an exceptional type of casing which is used in all its tyre ranges, such as the Maxi Traction, the Performer or the Utility range.
This casing is characterised by its resistance and far superior robustness and has been specifically designed to offer maximum durability, making the tyre perfectly suitable for repairs.
When you choose agricultural tyres from the Firestone range, you invest in the quality of the construction of the casing, which may play a crucial role in the event that your tyre incurs damages.
The solidity and reliability of its structure means that successful repair work can be carried out in the majority of cases, thus extending the useful life of your tyres and helping you to save money in the long run.
The choice of the brand and the range of agricultural tyres may have a significant impact on the repairability of your tyres should they become damaged.
Cold repairs are ideal for small punctures and must never be used for more extensive damage.
Hot repairs offer far more possibilities, but are only an option if the structure of the tyre is sufficiently resistant to cope with such repairs.
The investment in quality tyres is therefore a more sustainable and lasting investment if the tyres can be repaired, as opposed to discount tyres which don’t really offer this possibility.
We have developed a complete guide for you to download free of charge “Everything you need to know about mounting & demounting tractor tyres”
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