The wear rate study was considered appropriate due to the need to establish the most accurate correlation possible between new tyre declarations submitted by SIGNUS members, which represent the total weight placed on the market, and the obligation of the system to manage an equivalent amount, bearing in mind that tyres lose a sizeable percentage of their tread during their lifetime.

By way of summary, the results obtained indicate that the wear rate differs according to the category of tyre and specific account must therefore be taken of the category differences in producer members' placing on the market calculations.

The wear percentages for re-usable tyres are considerably lower than for end of life tyres, even if the average weights are lower in the former case (the opposite to what one would expect given the lower degree of wear suffered). However, this finding is accounted for by the size differences in the category overall.

A range of wear tests were carried out according to size, speed codes and even makes of tyres. Although some trends can be observed in this regard, the high number of variables and the complexity of the data do not, for the moment, permit a better correlation between these parameters and the wear rate to be established to arrive at more accurate values.



The work carried out to evaluate the technical and economic feasibility of end of life tyre thermolysis is based on trials with real materials from projects currently in progress and a detailed examination of the available literature by SIGNUS.

In thermolysis, tyres are reduced to a gas flow, a liquid fraction, carbon waste and metal. The distribution of the products obtained depends on the reaction temperature.

It was decided to carry out an evaluation of the technical and economic feasibility of thermolysis in view of the many existing approaches, most of them in the early research stage.

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The aim of the study was to determine the biomass content of an end of life tyre through thermogravimetric (TGA) and 14C analysis using, in line with reference standards, prepared samples which were representative of the different types of ELT on the market. The biomass content of each was measured using both methods (TGA and 14C).

In addition, the results obtained were compared with five standards with known rubber content to build the necessary calibration curve for the TGA analysis.The biomass content was also measured by 14C analysis.

By way of conclusion, 14C was found to be a valid and reliable method for determining biomass content and the results of the TGA standard calibration curve coincide with the actual natural rubber content in each case. Conversely, the thermogravimetric method is inadequate for determining biomass content as the results differ substantially from the true results.


Thermoplastic elastomers are materials with properties midway between rubbers and plastics. There are currently many industrial products on the market which are supplied by major petrochemical firms and have a wide variety of uses in different sectors.

The study involved formulating different polymers to obtain materials with properties close to or even better than those of conventional thermoplastic elastomers.

The study initiated in 2011 was based on a literature review which was carried out to identify the properties of thermoplastic elastomers containing tyre powder. Laborarory tests were then conducted to verify the results of the publications with the greatest potential for use, with a view to a more detailed R+D project.