Pirelli had a presence yesterday at the NEC Autosport International which is the major trade (and public show) for motorsport in UK / Europe. It is good to see the Pirelli support classic car owners including cinturato CN36 in 185 70 15 and 215 60 15 sizes*. Latest releases of these tyres receive good reviews in the German press comparison test on an early 911 also read positives from CN36 buyers here. A strong contender for folks seeking replacements it seems.
They are tubeless versions today, but that wasn't the case originally. I've read question about whether the CN36 (as the only tyre fitted originaly by the factory on 73 Carrera RS until Dunlops arrived) were originally tube or tubeless.
It is my understanding based on some evidence that the original version fitted on the Carrera RS was actually with a tube.
Redpctd references on RS and later Carrera 2.7 state factory change use of tubeless only happened during December of 1974 which would have been for impact bumper Carrera 2.7 (well after the limited edition RS had finished production). The change from Pirelli tube type tyres to the replacements with steel belt tubeless for the 215/60 15 (also the smaller from 185/70 15) is documented in sources that have access to factory production records. The use of the small valve support attached to rim on the 7/8inch wheel were introduced the very same day in December 1974 according to these sources -- not a coincidence, specifically introduced to support tubeless stems I suppose.
Original examples of the tube type CN36 are obviously well past sell by date and not for use beyond static display where every detail of originality is important, such as concours or museum. Neverthelss there are some folks here interested in finer points of originality so these photos is an early German made tube type Pirelli Cinturato CN 36 215 60 15 one of a pair taken off an original genuine RS with tube type markings. German made tyres, they are vintage items and only for Carrera RS or Carrera 2.7 at that date:
I have them in storage. Pirelli inner tubes too. Not saying these these examples were the actual ones factory fitted on my 1972 production date / model year 73 RS as part of the RS conversion order post homologation, of course.
However with the change from tube type to tubeless documented in respected RS reference sources as December of 1974 these examples were almost certainly made before that date because they are the tube type that were made by Pirelli for only a short time. Someting borne out by their DOT date markings being consistent with 1974. These tyres probably originate from Pirelli's Hoescht/Odenwald plant, in Germany. I think it is about 80 miles from Stuttgart?
Also as discussed elsewhere such tyres were often fitted on the original correct spec for early RS 6 and 7 by 15 inch Fuchs (not the now often seen 7/8 that only later became fashionable fit to last series RS or sometimes got fitted afterwards).
Wheel part numbers for 72/3 are discussed/well documented elsewhere so haven't duplicate part details of them in this post.
Never looked in detail at the internal profile of the later Fuchs vs the earlier three prong Fuchs regarding the dimensions and design of any internal "tubeless hump" on these Wheels. My car has its original factory wheels based on date stamp and presence of original RS only blue paint -- pretty sure despite originally having tube type they have a rim hump.
This generic information about tube hump shape is taken from a German Pirelli technical
booklet published around 1972:
For those who were asking those questions on factory original being tube type or tubeless for pre impact bumper: I'd say spec was the German-made tube type Pirelli Cinturato CN36, no rear valve support yet and the distinctive profile shape balancing weights sometimes applied prominently to the external rim as needed.
That in my opinion was as it was probaly done by the factory back in the day in late 72 and early 73. Don't believe the Model year 73 TES got Pirelli CN 36 when new from factory, particularly not the unique to RS 215/60 size?
The tube type version being original spec to Pirelli MY 73 is somewhat substantiated by photographs taken when the cars were new by absence of the stem supports. Also this particular datapoint in a road test report about the RS printed in May 1973 is very clear -- they were tube type :
Conventional wisdom can result in what we think was the original spec of the car obscured or lost over time! It takes research to find the in period proof as memory and opinion are often misleading and restorations destroy history or necessary later replacements of things can mislead.
The Carrera RS is to my knowledge the first road-car car to have been produced with a factory spec mismatched size front and rear wheel/ tyre axle pair so there is a small automotive historical footnote among such a small tyre specification details.
Not all the anorakish finer points that get looked into on this forum can claim to be about an automotive historical first.
Afaik tube variant CN36 are not available new from Pirelli these days, so this particular historical detail maybe moot however. The current reissue are the closest to original and by all accounts a worthy choice. Many folks might not care about correct to original spec details, but this forum is the place of countless such small early 911 originality and authenticity details matter for some --- folks who sweat such finer points.
The original old 215/60 15 (German made tube type version) were at one time very rare, sought out expensive items before the Pirelli reissue. I at one time had silly money offers to buy my examples from knowledgable folks. Being tube type they are not for sale even with the reissue
There maybe folks who have documented sources that know more/can prove it was different? Always open to learn from folks regarded as RS experts.
(*I've no affiliation to Pirelli or folks like Longstone who do much to support tyre supply classics from their base here in the UK.)
Steve
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