IMPORTANT INFORMATION REGARDING TYRES FOR HSCC CLASS 'D' COMPETITORS FOR 2011 ONWARDS

THIS IS THE CONTENT OF THE LETTER SENT TO ALL REGISTERED HSCC CRC COMPETITION MEMBERS REGARDING TYRES FOR 2011 ONWARDS. OF SIGNIFICANCE IS THE PROHIBITION OF USE OF ANY WET TYRES IN CRC PETER HANSON TROPHY BY 1000cc F3 CARS, AND ALSO THE MORE STRICT MONITORING OF THE CUT PATTERN FOR AVON TYRES.

ALSO REPRODUCED BELOW ARE THE TWO AVON DRAWINGS SHOWING THE CRITICAL DIMENSIONS FOR THE TREAD PATTERN CUTTING. ALL TYRES WILL BE CUT AT THE AVON HQ FROM THE START OF 2011 TO ENSURE ALL COMPETITORS USE THE SAME PATTERN. AVON HQ WILL ALSO SUPPLY THE EUROPEAN DISTIBUTOR SO THERE SHOULD BE NO VARIATION IN PATTERN ACROSS EUROPE. OUR APOLOGIES FOR THE POOR QUALITY OF DRAWING REPRODUCTION, HIGHER QUALITY DRAWINGS WILL BE INCORPORATED INTO THE CRC PUBLISHED REGULATIONS. FOR 2011 COMPETITORS WILL BE ALLOWED TO USE TYRES WHICH DO NOT CONFORM TO THE PATTERN DIMENSIONS PROVIDED THEY ARE NOT TOO FAR FROM THE DIMENSIONS SPECIFIED.

HSCC Classic Racing Cars – Tyres

Dear Competitor

Result of Request for Views
As you know I wrote to every registered CRC competitor early in November asking for their views on changes to tyre regulations for 2011 onwards. This letter was prompted by the discussion at the Silverstone Driver’s meeting and the subsequent confusion about what may happen.

A big thank you to all those members who expressed their opinion by email, letter and personal telephone call. Your views were very much appreciated.

The response was overwhelming support for ‘no change’ to what we have now. In fact the only different response from one competitor was if we could consider a different (softer) compound for Dunlop users if one became available, all the rest asked for things to be left as they are. Some of the comments were particularly welcome, for example Bev Bond was asked what they did about wet weather in period and he replied, “drive slower”, which I think sums up the entire subject. Other competitors pointed out we are not meant to be ‘works’ teams and the majority of us do not have those sort of resources, nor finance. All written replies can be made available via the office if so required.

I hope that we can now draw a very clear line under this subject, the Club will not be willing to undergo any further discussions on tyre changes including introduction of wet or ‘wet’ modified tyres (cutting extra grooves) in the future. The only time tyre regulations will be considered is if availability becomes an issue.

Wet Tyre Use in Peter Hanson Trophy
The issue of CRC Class D competitors entered in the Peter Hanson Trophy has been further considered by the Club. We have allowed those entering Peter Hanson Trophy to use ‘wet’ tyres, a measure introduced initially to encourage the European F3 Trophy competitors to enter our races. The ‘wet’ tyres used by these entrants up to now has been a modern super-sticky Avon tyre cut with a full wet pattern and has been a matter of much discussion and concern over the last year or two amongst other competitors and the FIA. Following the Monaco meeting in 2010 and FIA concerns about modern super-sticky wet tyres being used, 2011 sees the ratification of tyre regulations for any future Historic Monaco involving 1000cc F3 cars and this specifies that the ‘wet’ tyre must be the same (A37) compound as our current ‘dry’ tyre. Therefore, we have decided not to allow any deviation from our CRC Regulations in the future; from January 2011 onwards there will be no use of ‘wet’ tyres (or ‘wet’ modified tyres) allowed in any CRC race, including Peter Hanson Trophy. Thus no competitor will have any advantage in wet conditions. This decision has been brought about by recent changes to our Avon tyre pattern.

We have discovered that changes were being made to the specification of the pattern being used. These changes seem to stem from different outlets supplying tyres with a reduced groove and sipe (the sideways grooves) dimension, and sometimes with an elongated pattern. These changes create almost a slick when compared to our own approved supplier (BMTR) who now obtain the correctly cut tyres directly from Avon Motorsport headquarters in Wiltshire; this is the correctly cut tyre for all weather use.


This has been happening over the last 4 or so years, involving a gradual change to the length of the repeat pattern and also the width of the grooves. We have found that the width of grooves on tyres cut about 4 years ago was up to 5mm; in 2010 these appeared through some outlets with grooves only 2mm wide. The length of the repeat pattern 4 years ago was about 27 to 30mm and in 2010 it was sometimes 42 to 48mm. These tyres no longer look like the tyres we have used for many years, nor the illustrations circulated by Geoffrey Laycock in his example draft regulations. After considerable discussions and assistance from Paul Coates, General Manager of Avon Motorsports and Paul Smith of BMTR I have agreed with them that the tyres will revert to their original pattern as drawn by them in 1999.

We are taking steps to ensure that all tyres now delivered by BMTR for use in CRC in the future are correct taking account of groove width and tyre pattern dimensions. This will be clarified in the CRC Regulations for 2011. Those competitors who have purchased Avon tyres in the last couple of years which do not conform to the correct pattern and groove dimensions will be allowed to use their current tyres for 2011 only. Those competitors should be aware that they will not perform as well in wet conditions due to very limited water clearance, having grooves cut to only 2mm. Additionally we have been told that when the pattern is stretched this also significantly reduces grip in the wet. From 2012 onwards only the correct tyre will be allowed, this will need to conform to the Avon drawings H002 and H004, copies of which will be published along with the CRC Regulations. This rule will also apply to any European competitor who wishes to enter a CRC race, including the Peter Hanson Trophy.

So to be perfectly clear: for 2011 onwards there will be no changes to the CRC Regulations and wet weather tyres (or any tyres modified by cutting extra grooves) will not be allowed at all, not even for the Peter Hanson Trophy. From 2012 onwards tyres used by Avon competitors in CRC must conform to the Avon drawings H002 and H004. For 2011 we will allow any competitor with the non-conforming (dry) tyres to use them as we have no wish to cause additional expense to people who have bought them in good faith, unaware they may not comply with the specification.

Thank you for your responses to my request. I am sure that keeping CRC as a one-tyre formula for wet or dry conditions as originally specified, is the correct decision.


David Pullen Chairman, HSCC Classic Racing Cars

December 2010

TO VIEW THE DRAWINGS OF THE TYRE PATTERNS BETTER ENSURE YOUR MOUSE POINTER IS ON THIS PAGE THEN HOLD DOWN THE 'CTRL' KEY AND EITHER USE THE SCROLL WHEEL ON YOUR MOUSE (IF YOU HAVE ONE) OR USE THE '+' OR '-' KEYS TO CHANGE THE SIZE OF THE IMAGE

FRONT TYRE

REAR TYRE