Need help decoding tyre sizes

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    Author Topic: Need help decoding tyre sizes  (Read 4966 times)

    Offline OzCuda

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    Need help decoding tyre sizes
    « on: July 29, 2005 - 12:14:43 AM »
    I need a bit of help decoding the American tyre sizes quoted for 70s vehicles (this system not used here in Australia).  Need a decode for the letters used in F60x15, E60x15, G60x15, F70x14 etc.  I'm guessing the letters define a certain tread width and the 70 for example is sidewall height as a percentage as per current sizing. 

    Also wondering what the largest tyres available were for 70-74 cudas from the factory.  Cheers, Mark.
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    '70 Barracuda


    Offline ChallengerVert

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    Re: Need help decoding tyre sizes
    « Reply #1 on: July 29, 2005 - 01:16:58 AM »
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    1971 Dodge Demon 408 5 Speed

    Offline OzCuda

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    Re: Need help decoding tyre sizes
    « Reply #2 on: July 31, 2005 - 05:41:42 AM »
    Thanks for that - so the letters are the load rating of the tyres and the 60/70/80 is the aspect ratio, but of what tyre width?  Was the width and diameter of 1970s tyre pretty standard?  Apparently the biggest tyre for E-bodies was available on the Hemi cars - what was the width and diameter of these?
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    '70 Barracuda

    Offline MEK-Dangerfield

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    Re: Need help decoding tyre sizes
    « Reply #3 on: July 31, 2005 - 06:28:54 AM »
    Oz,
       60/70/80 is the width of the tire. Aspect ratio would be 205/215/225/etc.

      Mike
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    Mike

    1970 Challenger - SOLD
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    Offline CFster

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    Re: Need help decoding tyre sizes
    « Reply #4 on: July 31, 2005 - 01:57:37 PM »
    Quote from: MEKrunner on July 31, 2005 - 06:28:54 AM
    Oz,
       60/70/80 is the width of the tire. Aspect ratio would be 205/215/225/etc.

      Mike

    If you're talking about modern tire size designations, then I think you've got it backwards.

    P225/60r16

    P means Passenger tire
    225 is the width of the tire in millimeters
    60 means the height of the sidewall of the tire is 60% as high as it is wide, or 135mm - this is the aspect ratio
    16 is the rim diameter in inches.

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    Offline OzCuda

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    Re: Need help decoding tyre sizes
    « Reply #5 on: August 01, 2005 - 06:53:05 PM »
    Hmm, was thinking that 60mm wide tyres might look a little strange on the cuda :grinno:

    but still wondering - what was the diameter of the biggest tyre you could option on a 70-74 cuda :dontknow:
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    '70 Barracuda

    Offline IUU2ROC

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    Re: Need help decoding tyre sizes
    « Reply #6 on: August 01, 2005 - 07:08:05 PM »
    I found this information on an F body website. (and a V6 Camaro site at that  :ack:)

    Quote
    How can I convert my old tire size (F60x15) to its metric equivalent?

    The letters correspond to metric measurements with A=155mm through L=235mm ("I" is skipped). The number is the sidewall height to tread width ratio (just as it is now). For the F-bodies, the following conversion should work properly: E70x15 = P205/70R15, E60x15 = P225/60R15, F60-15 = P235/60R15, and G60x15 = P245/60R15.


    http://www.v6fbody.com/v6fbody_version_02.shtml
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