Alternative tyre to 205VR14 XWX

Ther is no doubt that the Avon CR6ZZ is a good gripping tyre and it does also have a carcass that is built by Avon with a good understanding of the kind of geometry a car of this period has. I am sort of a fan.

https://www.longstonetyres.co.uk/vintage-tyres/avon-cr6zz.html

There is always a 'However'. well i do have a few:

• They are racing compound tyres. those compounds deteriorate with heat cycles. I just don't like the idea of these tyres getting a few years old, specially with a few heat cycles under your belt.
• Often over sized tyres are fitted. you are supposed to have the back end come round a bit. Old rear wheel drive cars should oversteer. Its all part of the fun.
• They don't look right on an old car. I don't think they came out untill the 1990's.

There are probably more issues, but i don't want to bore you. On balance they are an great tyre. If i was going on the track i would be all over them (with some extra adverse camber), but on the road i would still be on Michelin XWX.

I think Daytona were 215/70VR15 front and rear originally, then i think Borrani started making a wider 9" rear for the 225/70VR15 tyres

https://www.borrani.com/ferrari-wheels/365-gtb-4-daytona.html

Incidentally a 225/70R15 tyres recomended rim width is 6" to 8" but Ferrari love fitting wider rims on the rear of their cars. Now i think here is the crux of the matter. fitting a tyre on a wide rim gives , yes more grip, but also predictable handling, i beleive it is for predictability and progressiveness of over steer that they fitted such a wide rim on the 512, and why it was used on the rear of the Daytona, they would have found out throught testing that the 225/70 was good on the track.

I am not convinced Ferrari would have fitted a wider tyre if it was available - becuase it was available! 60% profile tyres came out at the end of 1972. Ferrari didn't fit them, i beleive, because it didn't suit their chassis. What happened on the race track is another story, but for a road car i like a little less grip, i like it to not brake away, but to start to move a little on the rear end in a predictable, progressive and graceful manner that i can then control with the throttle pedal. "so i can look like Stirling Moss or Fangio"

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then this is what we got from Michelin regarding the over sized rear rims



Classic Car Tyres

46 rue du Ressort

63000 Clermont-Ferrand , den 18/05/200




Unbedenklichkeitsbescheinigung

Zur Vorlage beim TÜV



Hiermit bescheinigen wir als Reifenhersteller: Für die Fahrzeuge Ferrari 365 GTC 4 (Daytona)

N° chassis : 365 GTC4 * 14587

Höchstgeschwindigkeit : 245 km/h


es bestehen für vorstehend beschriebenes Fahrzeug keinerlei technische Bedenken, von Seiten des Reifenherstellers,


Fahrzeuge mit der


Erstausrüstungs Rad-/Reifenkobination 215/70 VR 15 90 W Michelin XWX auf Felge 7 ½ L x 15


durch folgende


Umrüstungs Rad- / Reifenkombination 225/70 VR 15 92 W Michelin XWX auf Felge 9 L x 15


an der Hinterachse zu ersetzen.


Die Freigängigkeit der neuen Rad-/Reifenkombination ist zu gewährleisten oder durch geeignete Maßnahmen herzstellen.


Die vorstehende Kombination wurde bereits zu Bauzeiten durch den Fahrzeughersteller, bzw. dessen Importeur freigegeben.


Mit freundlichen Grüßen


Manufacture Françaises des Pneumatiques Michelin

 

hmm yep its funny this tyre. it has been tricky pinning down a year for this tyre. we did at one point think 1972 but yep the SV Miura came out with 60% profile CN12 in 1971.

https://www.longstonetyres.co.uk/classic-car-tyres/lamborghini/miura.html

and the current Pirelli book states the CN12 as 1971 in its brochure

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but amusingly the Pirelli web site now says 1969

https://www.pirelli.com/tyres/en-ww/car/collection/product/cinturato-cn-12

However i'm pretty sure they weren't doing 60 profile in 1969.