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275 GTB originality

Discussion in 'Vintage (thru 365 GTC4)' started by Longstone Tyres, Apr 13, 2018.

  1. Longstone Tyres

    Longstone Tyres Formula Junior
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    Hi

    I'm trying to find out what were the original tyres on the 275 GTB. Currently there isn't really any other choice as you can see on here https://www.longstonetyres.co.uk/classic-car-tyres/ferrari/275-gtb.html there is only really a XWX that you would consider. Which isn't a bad thing because the XWX is brilliant and they were around in the late '60s

    However i think Pirelli were the first to get a 205 section tyre to be able get a V speed rating with the CN72 which came out in 1964. which i believe is why you see a massive transfer in the super cars of the period taking off 185Vr16 tyres and changinge to 15" wheels with a 205 section (a 185Vr16 is the same diameter as a 205VR15) so i know this to be the case with the cars on 15" wheels. But the 275GTB was on 14" wheels.

    So for now, regardless of what was OE, any pictures you see that are current, or for that matter 40 years old, (I know the CN72 was not made in 1980) will be on XWX because the XWX has constantly been available

    Does anyone know what the original tyres were?

    Does anyone have any evidence they are happy for me to have for my files? (ie build sheets)

    Incidentally i found these 2 old pictures with Pirelli tyres on and one of them is pretty definately Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login a CN72
     
  2. miurasv

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    #2 miurasv, Apr 13, 2018
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  3. johngtc

    johngtc Formula Junior
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    My 330 GTC, which has the same sized wheels, was delivered in Aug 1968 with Firestone Cavallino 205R14 tyres. I think this particular tyre was relatively short lived although it was also on the 365 GTC tested by 'Autocar' that same year.
     
  4. Longstone Tyres

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    Hi Muira SV

    Yep it looks like we tried before but weren't totally conclusive and i may have learned a little more since then. I believe the Dunlop in period would have been the SP 41, which i think did only have an H speed rating as that is all i believe Dunlop Radial tyres were capable of until 1968 when they developed the SP Sport (that was also known as the Aquajet. this tyre is still made in a few Jaguar sizes, but not 205R14 and they are not actually made by Dunlop either sadly) below there is an in house Jaguar bulletin discussing the SP41 tyres on Jaguar

    The Firestone Cavalino tyre is interesting. but again i don't think in period they would have been able to attain a V speed rating.

    i am keen to find out which Pirelli it was. I think CN72 or one of their close developments (there was also a CN73, and the difference is minimal)

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  5. lancia

    lancia Formula Junior

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  6. Daytonafan

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    Dunlop were Scuderia Ferrari's tyre supplier for F1 through the early sixties before switching to Firestone in 1966. While hardly conclusive it would make sense that a race car supply deal would also include supplying at least some of the road cars too. Firestone supplied the Ferrari F1 team through to 1973 when they moved to Goodyear.

    It is certainly true that Ferrari dropped Michelin as a supplier on the road cars during the Michelin/ Bridgestone F1 tyre war of the 2000's when Ferrari was very embedded with Bridgestone.
     
  7. miurasv

    miurasv F1 Veteran
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    Reading the letter attached to your post the SP 41 was restricted to 125 MPH and could not have been H rated so not suitable for a Ferrari and the SP41. H was only made in the 185 x 15 size. I don't think the V speed rating had been introduced in the 275 production time.
     
  8. lancia

    lancia Formula Junior

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    Note that the vintage SP 41 "Aquajet" is not the same tread pattern as the Dunlop SP Sport used on the 275. The SP Sport as originally on a 275 had a block-like dog bone pattern.
     
  9. miurasv

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  10. Longstone Tyres

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  11. lancia

    lancia Formula Junior

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    That photo is I believe from the 1964 Paris Salon. That is my point, it appears to not be the tire that you refer to as SP41. It is perhaps that Dunlop may have given the nomenclature SP Sport to more than one tire type. But I have seen numerous examples of the Dunlop SP Sport as in the Salon photo in the boots of original 275s and I have had that tire in my hand once upon a time.
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  12. lancia

    lancia Formula Junior

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    Hi Longstone, Apologies, I did not first expand and read all of your post. Send me a PM with your direct e-mail and I will share with you a photo that shows the tread pattern. I do not post because not my photo and has copyright.
     
  13. Longstone Tyres

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  14. Longstone Tyres

    Longstone Tyres Formula Junior
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    Er - how do i do a PM?
     
  15. lancia

    lancia Formula Junior

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    SP3 pattern somewhat similar, but that's not it. The 275 Dunlop SP Sport has the dog bone blocks continuous across the tread width, without any continous circumference strips around.
     
  16. John Vardanian

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    #16 John Vardanian, Apr 17, 2018
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    Is this the "dog bone" pattern? It's the only picture I have left and I didn't keep the tire either. I don't remember the Dunlop model number, but I do remember reading "Made in the Republic of Ireland" on it.

    john

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  17. Longstone Tyres

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    So what year do you think that tyre is?
     
  18. John Vardanian

    John Vardanian F1 Rookie

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    I suspected 1964.

    john
     
  19. Longstone Tyres

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    It does seem funny, because i didn't think Dunlop could make a V rated radial tyre that early in the '60s.

    i need to do some more digging
     
  20. 360C

    360C F1 World Champ
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    I have a copy of the build sheets for 275 GTB/4 # 10385. They state that it was delivered with Michelin - 205/14
     
  21. miurasv

    miurasv F1 Veteran
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    Build Sheets for 275 GTB/4 (Alloy) #9501 state Dunlop 205x14 HR.
     
  22. Longstone Tyres

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  23. miurasv

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    I looked into this a while back and of the info I looked at it stated the V Speed rating didn't come out until around 1971. I think I posted about it. If correct the Pirelli CN72 would not have been V rated in 1964 or at any time during 275 GTB production. Will look again...
     
  24. turbo-joe

    turbo-joe F1 Rookie
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    for what you need in the US H or V tires when you may not go so fast?
     
  25. miurasv

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    They are needed to match the handling/cornering and braking ability of the chassis, suspension and brakes, not just the top speed.
     

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