This question in title came up in another thread
Starting this as a separate thread At suggesting of others to avoid historical questions coming up among a thread about driving impressions of current CN 36 offering.
This is a thread to get evidence one way or another on how it was with Pirelli tyre offerings on TES from circa 69 to 73
As background it is understood generally that the Pirelli cinturato CN36 came out in late sixties —according to pirelli generic history 69 — no doubt it was in range of sizes for a range of Marques and models.
This of course does not mean it was in the exact size and speed rating in 1969 required for the 911 TES on 6 inch rims. Or even if it was of right size and speed rating the factory adopted it for 911 over other Pirelli offerings in use at that point. That’s hopefully what will emerge. Im not sure if Porsche used lesser speed rating than VR at this time for lower top speed T but it seems VR was used in T E and S as well as by RS for model 73.
From my Direct dealings with Pirelli recently asking questions about the reissue cn36 it is clear that due to the channels they use for niche classic vs core business the folks at Pirelli do not have the definitive history (hardly surprising for a big corporate it mirrors what we we see of Porsche AG lack of depth from “customer service” on their product of five decades ago).
From my personal archives I’ve a few data points I’m happy to share here as a discussion starter, not exhaustive / conclusive.
So far these do seem to point to the adoption of cn36 on 911 TES being no earlier than model year 72 (but other hard evidence coming forward from ESR community might change that initial impression):
Here is what I have to kick off:
1) road and track edition February 1972 features a 911E. It is the only thing from back in the day from a trustworthy source I’ve found so far that names a specific Pirelli product in use on that 911. The tyre at that point is a CN 72 .... interestingly not a CN36 that some here may have presumed was the Pirelli tyre for 911 by 72
A comment mentions the USA importer so it seems reasonable to assume car used is the representative spec they provided to prominent publication for a significant road test of a 911. Other tyre brands were used like Michelin and Dunlop but were others beyond the cn72 ( Like Cn36) also being used?
2) the supplier is specifically Veith Pirelli a company Porsche bought in Germany in early 60s
Further digging in my reference papers suggests the 185/70VR15 CN36 may still have been in preparation at that point
3) I happen to have a 22 July 1971 Veith Pirelli preiseliste among my collection of old references date so roughly coincident with the 71-72 model year switchover and maybe even production car being tested
4) the Veith Pirelli booklet shows at least two tyre types that might seem most relevant to 911 which I assume would require VR speed rating as per the E spec in the R&T test
5) assuming all Porsche 911 would require VR speed rating of 185/70 15 this is the entry in the Veith Pirelli price list
6) there is a footnote *) against the Cn36 “in vorbereitunng” which I think ( subject to confirmation by native German speaker) means in preparation.
7) taking these pieces of information together suggests that around the beginning of 72 model year the 911 had cn72 185/70 VR 15 because the CN 36 despite being around since late 60s was “in preparation” so not yet available for use at that time.
8) by early October 1972 the 73 Carrera RS was launched in Paris. While I could provide a lot of evidence it is a well known fact that the model drew attention to the use of Pirelli CN36 specifically because of a small historical first for a roadcar: use of different size 6&7 15 rims front and rear with different sized tyres. 185 70 VR 15 front and 215 60 VR rears. In addition to the front to rear axle difference the 60 then low profile was a new innovation on roadcar. Pirelli for a while were the only available source of this RS combo until Dunlop caught up and some RS got that brand. Since this is well known I won’t provide photo evidence as it is probably redundant on ESR.
9) the Pirelli tyres used on the RS through production and until December 1974 in the G Series 2.7 Mfi were tube type and man made (nylon or rayon or whatever man made radial belts) but Porsche is known to have switched to steel belt tubeless cn36 in December 1974. I actually have an early tube type non steel cn36 in my original RS parts stash and can check the material if it becomes relevant; but certainly not steel belt or tubeless at first!
A few questions:
a) is what evidence is there from factory or verifiable in period sources that the TES series production cars got CN 36 185 70 VR 15 tyres before the RS used them Around autumn 72? If so when did they supersede the cn72 that was evidently the German made Pirelli on the R&T road-test example?
b) are there other examples of the CN 72 variant being the tyre the Pirelli factory used beyond that one R&T verified example?
Probably best to leave Michelin Dunlop etc other makes to one side; not sure if this particular thread should go back to Pirelli before the cn 36 even existed 69?
I don’t have an axe to grind because fortunately I know exactly the factory tyres on my car in December 1972. Compared to some parts the factory tyre fit Evolutions is maybe less well documented here. One of strengths is when ESR works to establish facts rather than accepting vague presumptions. Of course exceptions etc apply to confuse but often sufficient patterns emerge so maybe it’ll become clear if CN tyre was used significantly (or not) before it appeared on 73 RS.
I don’t know but based on the above points showing CN 72 verifiably in use Feb 72 my hunch is maybe not. Maybe cn71 like seen on that Roadtest E was used for Most longhoods as Pirelli offering. At least until RS with its mismatched sets arrived a bit after summer shutdown. Maybe the Veith Pirelli “in preparation” footnote soon became production ready and the CN 36 did see significant use spring and summer of 72? Let’s see if there is info to shed some light.
Suggested to kick this off if it clarifies some of the assumptions and inferences that were potentially confusing on the other thread. Up to folks with TES to use thread to get better understanding of Pirelli on 911 — or not.
While I prefer to see what the evidence says somehow with the “in preparation “ footnote comment on that relevant VR size spec it seems more likely time needed to complete development and ramp up and consume any cn72 in extended supply chain; possibly begin to see CN36 use scale up at start of model year 73. Unless that footnote comment is completely wrong and the R&T cn72 example in my magazine is a total anomaly can’t see the Cn36 being the Pirelli tyre type referenced on a 911 MY 70 kardex. I have a Porsche rare engineering publication published around 72 that shows CN36 at Porsche undergoing a rig test but without a specific date doesn’t pinpoint. Other photos in the book generally are around 72 however. Odd exceptions like all things Porsche not withstanding! I’m guessing we see the CN 36 become a popular offering for MY 73 and more commonplace tyre on TES by springtime 73. Be interesting — open to be proved wrong inferring too much on the initial evidence presented above as as starter.
Steve
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Originally Posted by 911MRP
