Hi

Some time ago a German magazine called Autoblid Klassik did a proper modern tyre test on the classic tyres that are available for early 911.

http://www.longstonetyres.co.uk/page...-porsche-tyres

The web page link above has the article on it which has been translated to English. Then there is Porsche's recommendations for tyres for their classic cars. Then top left there is a link to a web page called Klassic Porsche Reifen which has the original article in German.