Technical Tire Management – Part III

Is it viable to retread tires of heavy equipment? How can one calculate the maximum number of times a tire can be retreaded? Find these and other answers in today’s article, "Maintenance Technical Management – Tire Management III."

Many fleet maintenance managers may still question the economic, safety, and environmental benefits of retreading tires. Well, what you may not know is that:

• Retreading a used tire costs between 7% and 25% of the price of a new one.
• Retreading extends a tire’s lifespan by about 40%.
• 90 liters of petroleum are required to make a new tire, while only 27 liters are needed to retread a used one.
• Companies performing this type of repair must be certified by INMETRO, and for passenger cars, pickup trucks, and vans, retreaded tires must be identified. To locate certified INMETRO tire retreading facilities, access the link: https://registro.inmetro.gov.br/consulta/Default.aspx?pag=1&acao=pesquisar&NumeroRegistro=&ctl00%24MainContent%24ControlPesquisa1%24Situacao=Ativo&dataConcessaoInicio=&dataConcessaoFinal=&ObjetoProduto=Servi%C3%A7o+de+Reforma+de+Pneus&MarcaModelo=&CodigodeBarra=&Atestado=&Fornecedor=&CNPJ=&ctl00%24MainContent%24ControlPesquisa1%24SelectUF=ES&Municipio=;
• Tire retreading can be divided into three types:

1. Recap:

In the recap process, the tread (the part of the tire that contacts the ground) is replaced. Recaps are commonly used for truck and bus tires, with a key advantage for heavy vehicles, as the process can be done up to six times per tire. However, only heavy-duty tires are designed to withstand this many retreads, as they were built for this purpose. The area where the recap is done can be seen in the red region in the image above.

2. Recut:

In this process, both the tread and the “shoulders” (outer part between the tread and the sidewall or the lateral part of the tire) are replaced. Recutting involves removing the worn tread from the tire casing and then applying a new tread through a vulcanization process. For a tire to undergo the recutting process, certain conditions must be met, such as no cuts or deformations, and the tread should not be completely worn down, as discussed in our previous article. Additionally, there is a limited number of times a tire can be recut without compromising its performance, meaning that after a certain point, the old tire becomes technically unviable.

3. Remold:

In this third type of retreading, the entire surface of the tread and sidewalls is reconstructed. This procedure involves removing both the tread and sidewall portions of the tire. An important note is that remolded tires are not new; they are new products made from used casings, as they use these as raw materials.

It is important to note that tire reuse depends on the condition of the tread at the time of replacement. If the tread that contacts the asphalt is excessively worn, as discussed in our previous article, the tire may not be reusable.

How long is it worth retreading tires?

To answer this question, some data from mobile fleet industry will be used, specifically considering trucks. To determine how long it is viable to retread tires, we can use a table similar to the one below. This approach provides a good sense of the total repair cost per retread, as well as the cumulative cost.

As shown in the table above, there is an increase in cumulative value after the third retread. This is clearer when observing the chart below:

Observe how the repair cost per 100 km decreases from the new tire to the first retread. It’s quite significant. However, the cumulative tire cost also rises considerably after the third retread, and the tire’s useful life is reduced by 63% compared to a new tire. From the third retread onward, continued repairs become unviable. If the cumulative cost remained low after multiple retreads, structural aspects of the tire should also be considered to determine whether further retreading is viable.

In conclusion, I hope I’ve helped maintenance managers gain a better understanding of the importance of the retread process in maintenance cost composition. Although Brazil is the second largest tire retreading country, behind only the USA, it is still common to see asset managers avoiding retreading their tires. In other words, poor tire management increases maintenance costs.