European tyre makers "Cannot meet" EC noise target suggestions - Bonus feature

By David Shaw, ERJ editor

Brussels - Europe's tyre industry has responded to a consultation document from the EC saying it cannot meet the tyre noise discussion targets unless the European road industry also contributes. The industry has also called for mandatory tyre pressure monitoring systems that are accurate.

On 7 August, the European Commission began a public consultation procedure for proposed new legislation affecting the vehicle manufacturing industry. The discussion document included figures for discussion covering tyre pressure monitoring systems (TPMS), limits on noise emissions from tyres; limits and ratings for rolling resistance of tyres and some ideas for wet grip standards for tyres. All comments on the discussion document were to be with the EC by yesterday, 18 October.

The industry's representative body, ETRMA (European Tyre and Rubber Manufacturers' Association) has responded in two ways, first with a formal response to the proposals and second through a letter to the Commissioner for Enterprise and Industry, Günter Verheugen.

In its formal response, ETRMA said the noise limits presented in the document are, "unrealistic and simply cannot be achieved by the Tyre Industry." (Emphasis by ETRMA).

The EC is likely to bring in new laws based on future discussions. These are likely to come into force from around 2012. The figures were based on recommendations contained in a research document prepared by FEHRL, (the Forum of European National Highway Research Laboratories).

FEHRL concludes that most existing tyres fall well within existing noise limits and the journey from the current market situation to the proposed new limits is a relatively easy one which should not, in any way, compromise safety.

ETRMA says in its response, "The Tyre Industry disagrees completely with the FEHRL Study."

ETRMA has three fundamental arguments with the methodology of the FEHRL study.

First, says ETRMA, the study investigated insufficient tyres to draw reliable conclusions

Second, the ETRMA says the study did not actually test any tyres; it looked only at pre-existing data and that data was accumulated under varying test conditions and on different road surfaces.

Third, the conclusions did not adequately take into account the market segmentation within the industry.

Together these three points mean the conclusions drawn by the report cannot be taken seriously, said an ETRMA spokesman.

The second point is perhaps the most telling. Although the noise test method is well described in the test methodology, the road surface is not so well described. One key limitation of the ISO standard is that it does not adequately specify the depth of the asphalt on the ISO road surface. Two road surfaces which both meet the ISO standard can deliver noise results on the same tyre that are up to 8dB apart, said an ETRTO noise expert nominated by ETRMA. The expert's employer declined to permit the name of the expert to be revealed.

The noise expert said that because the test data used by FEHRL was collected on different road surfaces under different conditions, the results are not reliable, and should have a ±6 dB error bar on them. This means conclusions which appear to show that many tyres are today 3.5 dB quieter than the legal limit, cannot be drawn from the data used by the FEHRL researchers.

The third problem with the FEHRL test, according to the ETRTO/ETRMA spokesman, is that the study fails to take account of the market segmentation.

The problem, said the expert, lies not at the narrow, low performance end of the spectrum (class C1A), but with the wider tyres and with truck tyres. Although roughly half the tyres in the FEHRL test appeared to perform well, that does not mean it is possible to make all tyres meet the same stringent standards.

It is like trying to improve fuel efficiency in cars, said a spokeswoman for ETRMA. While it might be possible to make a VW Lupo deliver 3litres/100km, that does not mean it is possible to make a Ferrari or Lamborghini deliver the same fuel economy. The tyre industry, she said, accepted that some segments of the tyre market could achieve the figures in the document, but said firmly that it would be impossible to make all tyres meet the limits.

In the public consultation document, the EC requested comment on a series of figures which would mean car tyre noise emissions would have to decline by around 5 dB from their current levels and truck tyres would have to decline by around 6 dB. Data shown to ERJ suggests that this is beyond the laws of physics.

A modern tyre, launched in March 2006 is quiet by modern standards. In size 225/55R16 V it generates 74.9 dB(A), well below the current legal limit of 76 dB(A). All tests were carried out to the appropriate ISO standards. The numbers in the discussion document would bring the limit for this tyre down to 72 dB(A). This decline of 3 dB is equivalent to halving the noise level -- or going from four tyres to two.

Since most of the noise come from the tread, the design engineers first looked at the tread. Removing the tread pattern entirely -- turning the tyre into a slick tyre- will bring the tyre within the noise limits discussed in the public consultation document, but at huge costs to safety. With the slick tyre aquaplaning commences at much lower speeds and wet braking performance is severely affected.

Other measures designed to minimise noise, such as increasing the under tread by 5mm to add mass and damp down the vibrations which lead to noise, lead to similar loss in performance, but even less improvement in the noise emissions.

The ETRTO/ETRMA expert said that in general with tyres, it is possible to lose around 4 to 5 dB by adopting extreme measures, such as turning the tyre into a slick, thickening the undertread and other measures. The consequence, however, is a tyre that is completely unsafe for use on the roads.

Because the ETRMA disagrees so strongly with the FEHRL research, upon which the EC has based most of its suggestions, the organisation has found it hard to come up with suitable and constructive responses to the consultative paper.

In its response to the ideas on rolling resistance, the ETRMA said it wants to link rolling resistance criteria with a demand for mandatory fitting of 'accurate' tyre pressure monitoring systems. Use of he word accurate here means systems that can detect a small pressure loss in one tyre within a short time, and alert the driver to the loss of pressure and the specific tyre affected. ETRMA said it does not want to get involved in a discussion of technologies, but it did not feel that indirect pressure measurement systems could meet this requirement.

In a final response, the ETRMA said any new rules must be properly enforced, especially with regard to imported tyres, if the industry is not to be disadvantaged by the new rules. ETRMA said that it is easy to identify tyres made by ETRMA members - including Michelin, Goodyear, Bridgestone Pirelli, Continental and Cooper Tires - simply by looking at the sidewall. But it is more difficult to monitor rolling resistance and road noise of imported tyres. ETRMA said there is significant cost associated with developing tyres that meet the proposed rules. If imported tyres do not meet these rules, it expects that the authorities will prevent those imports from being used in the EU region.

The EC is now analysing the responses to the discussion document and will in the next few months come up with formal proposals which will then be discussed before any legislation is drafted.

This is a brief introduction to the topic. A full feature will appear in the next issue of European Rubber Journal

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Consultation page on EC website