Are retreads dangerous? How sustainable and safe are retreaded tires?

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Hand on heart: Would you also rather buy a cheap new tire than an equally expensive retreaded car tire? Although the more sustainable? The BAYERN 1 environmental commissioner clarifies how good and safe recycled tires really are.

By: Alexander Dallmus

Status: 12.10.2020 | Archive

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Are retreaded tires worse?

The retreading of tires was common practice in the Federal Republic, especially in the post-war years. In the GDR, every second tire was even retreaded until the end, which resulted from the shortage of material. Retreading of old tires was primarily carried out in order to be able to meet the daily demand in the still young Federal Republic at all. At that time, however, materials and processes were used that are not comparable with today’s state of the art. But this is exactly the reason for the prejudices against retreaded tires that still exist today.

Also at the start in Formula 1 racing: retreaded tires

In the commercial vehicle sector, in the earthmoving machinery sector, and even in motor racing, retreading is completely normal. In the aircraft sector, retreading is the order of the day. Aircraft tires are retreaded up to five or six times. Retreaded tires are also used in racing at speeds of over 300 kilometers per hour.

How are retreaded tires made?

Not only look like new: retreaded tires

The tread depth of a tire must not be less than 1.6 millimeters, otherwise the tire may no longer be used. In principle, the retreader does nothing other than restore the tread rubberization and a thin cover layer in the sidewall area to ensure an optimal appearance and bring the rubberization back to the level of a new tire. Rubber compounds of comparable quality are used for this purpose. Multi-layer processes are also used to optimize the tire’s rolling resistance. A compound is applied to the tread surface that is also used in the same or similar way in the new tire industry. This means that no restrictions have to be accepted in terms of concentricity and driving behavior.

“When tires are retreaded, the tread, that is the area where the tread is, is rubbed off, abraded, and then what is left is checked very elaborately for damage. And when the carcass is perfect, a new rubber is applied and then the tire goes into an oven, is vulcanized and gets its new profile.”

Thomas Schwarz from the vehicle technology department of ADAC Sudbayern

A great deal of technology is now used in the process, which also makes the procedure correspondingly cost-intensive for the business. For example, state-of-the-art technologies such as cherography, pressure testing, and in some cases X-ray processes or nail hole detectors are used to ensure the highest level of safety. This expense has consequences for the business, says Michael Schwammlein of BVR, who also serves as technical secretary of BIPAVER, the European retreading association:

“The financial outlay to run a professional retreading operation has increased so much that we are seeing massive losses across Europe. So that the market shares in the retreaded range, which concerns the tire replacement market in the passenger car range, lie surely clearly under one per cent.”

Michael Schwammlein of the Bundesverband Reifenhandel/ BVR, and Technical Secretary of the European retreading association BIPAVER

In Germany, car tires are still produced in the plants of the company “Rigdon GmbH” in Gunzburg and from “Reifen Hinghaus retreaded in Dissen (Lower Saxony).

When is a tire new and when should winter tires be replaced? You can read about this and much more in our article “Tips for storing your summer tires”.

The carcass – the crucial tire structure

The basis of any retreading, regardless of tire segment and tire type, is always the worn tire, the so-called carcass. The carcass is, so to speak, the supporting structure in rubber tires.

The tire carcass is the heart of the tire. The carcass contains the bead core, i.e. the area where the tire sits on the rim. It is therefore the direct link between the vehicle and the road surface. In addition to the sidewall and the fabric plies made of different materials, the carcass also contains the belt plies, which are installed at different angles. The aim is to guarantee the car maximum stability and safety even at high speeds and extraordinary driving maneuvers. Each tire manufacturer has its own “recipe” for its carcasses, of course and that’s why Thomas Schwarz of the German Automobile Club (ADAC) has certain concerns:

“As a customer, I can end up with carcasses from four different tire manufacturers on my car, which all look the same from the outside, but can have different driving characteristics.”

Thomas Schwarz from the vehicle technology department of ADAC Sudbayern

The problem could be solved, for example, by manufacturers attaching a chip to their carcasses and storing the necessary information for the retreaders on it. However, manufacturers are unlikely to be eager to reveal the exact composition of their carcasses.

For Michael Schwammlein of the German Tire Trade Association, on the other hand, it is much more important that the tire’s load-bearing structure is already designed for a multi-life strategy in the new tire concept:

“This means that if the carcass is already given a potential as far as deformation and deflection cycles are concerned, i.e. it is designed for a second life, then the retreader has a basis which is so good that one can say that a retreaded tire is absolutely comparable with a new tire product.”

Michael Schwammlein Federal Association of the Tire Trade and European retreading association BIPAVER

In the passenger car sector, the volume of scrap tires is so high that the retreader has plenty of choice if there is the slightest doubt about the quality of the carcass.

Scrap tires are an increasing environmental problem

Around 60.000.000 tons of scrap tires are produced in Germany each year.

In Germany alone, almost 60 million used tires are generated every year. That is the equivalent of a good 600.000 tons of material that must be collected and also stored. Although recycling possibilities have multiplied in recent years, only about half of the end-of-life tires are actually processed into rubber granulate, for example. The scrap tires are shredded to such an extent that the rubber can be separated from the metal struts in the tire by a screening process. A large proportion of this granulate is later processed into artificial turf or running tracks on sports fields. But the retreaded tire granulate can also be found as dampers in washing machines, in insulating mats or in electricity pylons.

There are already promising attempts to break down old tires back into their original components. In the so-called pyrolysis, steel, soot, pitch and oil can be obtained as raw materials in the thermochemical decomposition process at up to 800 degrees. However, the process is still very complex and cost-intensive and therefore not economical.

How to recognize retreaded tires?

Each tire may only be retreaded once.

Retreaded tires are not subject to the tire label requirement. According to the EU regulation on tire labeling, manufacturers of new passenger car and light and heavy commercial vehicle tires have been obliged since 2012 to indicate a fuel efficiency class for each of their products, as well as the wet grip class and the external rolling noise class. But of course there are also strict legal requirements for retreaded tires and also internationally valid minimum standards: Each passenger car tire may only be retreaded once. Recycled tires can be identified by the (Economic Commission for Europe) ECE numbers 108 for passenger car tires and 109 for truck tires on the side, as well as – similar to eggs – a code for the country that issued the approval. For Germany, this is “E1 . In addition, “retreading” is necessary or “retread be marked with the respective date of retreading. Tire size, speed class and load index are of course – as with conventional tires – also indicated.

Tests that motorists like to refer to before buying a set of new tires hardly exist for retreaded tires. Thomas Schwarz from ADAC Sudbayern also admits this:

“ADAC has done very little testing with retreaded tires because the market does not accept retreads.”

Thomas Schwarz of ADAC Southern Bavaria’s vehicle technology department

On the one hand, of course, this is understandable, but on the other hand, it gives drivers little to no chance to compare driving behavior in relation to price with other providers. Michael Schwammlein of the BVR can refer also only to internal tests of the Runderneuerers “Reifen Hinghaus” from Dissen in the Teutoburg Forest in Lower Saxony: “And it achieves absolutely comparable values in these areas in terms of both rolling resistance and wet grip, as is also achieved by a premium new tire.”

Then nevertheless rather the cheap, but new tires

A major problem in recent years has been the cheap tires from China that have flooded the European market. Retreaded tires are still a little cheaper, but the savings are for many motorists not purchase decisive, says Thomas Schwarz of the ADAC Sudbayern. “We have a lot of cheap new tires on the market, where the price advantage is then also relative again. Many buy then nevertheless rather the new, before they take which, where they do not know the history.”

In the low duty size ranges, the retread tire is hardly worthwhile anymore. That’s why retreaders tend to focus on the larger sizes, winter and all-season tires, or mixed road and off-road use, says Schwammlein “where new tire prices are in a range where the retread tire is really competitive with a savings of 40 to 60 percent.”

There is a future for retreaded tires

The bad image of retreaded tires in large parts of the population is one problem, but the public authorities could also position themselves more clearly. For example, retreaded tires are generally excluded from police tenders, even though safety and quality standards should not play a role.

Especially in the commercial vehicle and transport sector, the use of retreaded tires is still expandable.

“In the truck sector, a heavy truck tire saves about 50 kilos of scrap material and a considerable amount of CO2 expenditures in production. The mountain of used tires is growing. The question is, how long can we afford to keep working like this, when we have the opportunity to create a quick win?.”

Michael Schwammlein German Tire Trade Association and European retreading association BIPAVER

With the “De-minimis” program For example, the federal government also uses public funds to promote environmental protection in companies that transport heavy goods vehicles by road. In this case, it is also possible to apply for subsidies for investments in retreaded vehicle tires.

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