Hot and cold retreading: How it’s done

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Hot retreading and cold retreading are the main procedures that extend the life of tyres without compromising their quality and performance. They constitute a reliable and environmentally friendly solution that drastically reduces raw materials use and carbon dioxide emissions.

With over 25 years of experience in retreading, Radburg is the largest Romanian tyre manufacturer, importer and exporter. Our activity was born from the desire to produce locally and sustainably, to support the country’s economy and protect the environment.

The production process consists of maintaining high standards by using trained personnel and advanced technologies. We have the technology to retread passenger car tyres, 4×4 tyres, commercial van tyres, and commercial truck tyres. The quality standards of our retreaded tyres are recognized and constantly proven by our customers’ satisfaction in the national and international market.

Both the hot and cold retreading have a series of steps, from selecting the right tyres to the final inspection.

We start by sorting used tyres according to fixed criteria such as size, origin, year of manufacture, load and speed ratings. During this step, our specialists decide which cases go towards retreading or recycling. It is worth noting that, we select only premium brand tyres from certain countries such as Switzerland, Germany, Austria and others.

After this selection, interior and exterior inspections are made using inflation and control machinery. They are electrically and pneumatically tested to observe the internal defects.

The tyre is inflated to a pressure that is 30% higher than recommended to test its strength and highlight other defects. It is done with the help of special devices that detect damage in the sidewall, inner liner, or other parts. 

The stereograph inspection is decisive in the case’s journey. It uses coherent light or coherent sound waves to provide information about the quality of the case.

The tyre is then heading for the next step. It is important to note that we use only the hot retreading technology for passenger car tyres, 4×4, and commercial vans, while for the commercial truck tyres, we have the technology for both hot and cold retreading.

Mould cure or hot retreading 

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The hot retreading process is quite similar to the production of a new tyre. The first step is the buffing of the tread and the sidewall, so we are left with the inner case. The rubber powder is collected and used in other products such as rubber pavements; the smoke is retained with a special filter. 

Throughout the retreading process, each tyre is constantly examined to ensure its quality. The buffed tyre case goes on to the next step, where it passes through another inspection of the entire inner and exterior surface.

The second step in the retreading process is applying liquid rubber onto the tyre case to create an adherent layer and protect against oxidation. It will strengthen the bond between the tyre case and the new rubber coating.

Afterwards, the tyre goes through a static balancing machine so that the new layer will be applied uniformly, and the tyre will be balanced.

Now we reached the most interesting step, applying the new rubber. After a top-quality unvulcanized tread rubber is applied, the tyre case is placed in a mould for a certain period at a standard temperature and pressure. The mould shapes the new tread design, similar to the procedure used in new tyres production.

The last step is quality control and buffing any excess rubber. The tyres are individually inspected by our specialists. Each is inflated to a pressure that is 30% higher than recommended, and if any defects are detected, the tyre is examined and subjected to a stereograph test to find the cause. 

Precure or cold retreading 

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The cold retreading process starts by removing the tyre tread but keeps the sidewall with the original inscriptions. The rubber powder is once again collected and used in other products. 

Throughout the retreading process, each tyre is constantly examined to ensure its quality. 

Possible defects are manually repaired and filled by our trained employees.

A thin layer of rubber is applied to the tyre case to strengthen the bond with the new tread. The pre-cured rubber with the tread design is applied to the tyre.

Afterwards, the tyre is covered with a rubber envelope to create pressure on the casing. The tyre goes into the curing chamber for a specific time and temperature to properly cement the new layers. 

When the tyre comes out, it’s ready for the final inspection through a stereograph. 

Tyres can undergo the retreading process only once.

We do not accept tyres for retreading if they present one or more of the following damages:

  • Damage on the inner liner;
  • Damage of the steel belts, on the steel or textile wires;
  • Damage on the sidewall area;
  • Irreparable cracks on the tyre till the cord body;
  • Cracks or other damages of the cord body;
  • Oxidation of the cord body or steel belts;
  • Signs of corrosion due to oil or chemicals exposure;
  • Previous non-compliant repairs;
  • Multiple damages too close to each other;

Tyres that cannot be retreaded go towards recycling and energy recovery. Some tyres are shredded and melted, the resulting rubber being used in the retreading process. Others are destroyed in a thermal process that generates thermal energy. Thus, we eliminate the issue caused by the abandoned tyres and recover energy from waste using industrial processing.

By using retreaded tyres, you are actively protecting the environment. This industry helps reduce oil consumption in the EU by saving 500,000 tonnes annually. For the production of a new tyre, approx. 28 litres of oil are necessary while retreading requires only 5.5 litres. In addition to high-quality standards for our products and services, environmental protection is an essential component of our company.

Our product catalogue contains mod cured (hot retreaded), pre-cured (cold retreaded), new and used tyres. Explore it and choose the right ones for you.

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