Bias ply tire and DOT markings questions - NCRS Discussion Boards

Bias ply tire and DOT markings questions

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  • Louis T.
    Very Frequent User
    • July 31, 2003
    • 282

    Bias ply tire and DOT markings questions

    Hello all,

    I received the following photos from a fellow member down under. The photos are of the BFG Silvertown 7.75-15 4-Ply bias ply tires on the restored '66 he bought and brought over from the States in December of 2004. All five tires on the car are the same, in excellent shape, and mounted on the original Kelsey Hayes wheels.

    What do you all make of the DOT markings, and more specifically, the date code? Since a date code of "7254" doesn't make sense, the only logical interpretation appears to be that the "7" is part of the "C2F7" code, leaving the date code as the three-digit "254," hence the 25th week of 1974, 1984, or 1994. Or is there some other interpretation?

    Also, based on construction, tread, and sidewall appearance, are these, in fact, repros, or are they DOT-era originals?

    And two additional points of trivia:

    When did OEM manufacturers like BFG stop making these types of tires?

    When were repros of these and similar tires first produced by Coker, etc.?

    Thanks.

    Louis

    Attached Files
  • Jack H.
    Extremely Frequent Poster
    • April 1, 1990
    • 9906

    #2
    Re: Bias ply tire and DOT markings questions

    Guess, I'll take a stab. The tires you show are reproductions. Why? DOT legislated source traceability coding starting 1/1/68. Then, each tire mfgr made up its own code sequence to embody the information DOT required and treated their sequence(s) as proprietary information.

    In early 1971, DOT changed rules and 'standardized' the traceability codes into an 11-character sequence (12-characters for tires made after the turn of the century). The significance of each letter/digit in the standardized DOT sequence is no secret and there are many places you can get 'decode' instructions from including many, later, NCRS JG manuals from the Shark era as well as the archives here...

    The last three digits of the ID code (4-digits for tires built after the turn of the century) represent the date of manufacture in WWY format. The tire shown in your picture reads '254' meaning the 25th week of 1974, 1984 or 1994.

    Reproduction tires have been around since the late 70's and even though they're 'reproductions' they have to comply with DOT manufacturing requirements which is why they have a DOT sequence molded into them.

    BTW, tell your friend down under that NCRS is alive and well in Australia these days and he can join the chapter there for fellowship and help/assistance! They even have two judges who became the first outside of North America to garner NCRS Master Judge status....

    Comment

    • Louis T.
      Very Frequent User
      • July 31, 2003
      • 282

      #3
      Re: Bias ply tire and DOT markings questions

      Hi Jack,

      Thanks very much for the info. He is a member of the local Chapter there and has participated in the judging process (in fact, he'd informed me that he'd had his car Top Flighted). He contacted me because of the Restorer article I had written, but since some of the questions that resulted from our communications were beyond me, I thought I'd pass them along to the TDB. I don't know whether he first asked the right folks in his Chapter and didn't get the answer(s) he was looking for, or simply came to me first thinking I was an expert on the topic, but my first instinct is always to try to get an answer for someone even when I don't know myself. I will pass along your advice and encourage him to use the TDB directly as well.

      On a side note, I knew the tires weren't original to the car based on the appearance of DOT markings, but didn't know enough about the rest of the tires' construction and appearance to know whether they could have been real BFGs - just ones, say, manufactured in the '70s or '80s. If that was the case, they wouldn't have been repros per se (maybe my definition is wrong, but I consider something a repro when it isn't made by the original manufacturer), but simply "real" tires that are dated (obviously due to the very existence of DOT markings) after the production of the car.

      Thanks again.

      Louis

      Comment

      • Tom R.
        Extremely Frequent Poster
        • June 30, 1993
        • 4099

        #4
        Re: Bias ply tire and DOT markings questions

        Louis:

        My somewhat educated guess puts them as a 1974 manufactured tire. I've done some study of late 70's, early 80's date codes and the TIN (tire identification number) but specifically with Good Years. The TIN is what is regulated by DOT. Two considerations would cause me to date those tires as 1974.

        1. The "DOT" began to appear above the stencil plate in the early 80's...your tire shows it preceding the stencil plate.

        2. In the early 80's we begin to see the stencil plate be segrated into both an embossed element and a stencil plate. Your tire is a single stencil plate, characteristic of tires manufactured in the 70's. I would suspect an 1984 tire would show multiple stencil plates including an embossed component.

        Their is a portion of the TIN which does not change and so in later years we see the first portion of the TIN embossed versus commited to a stencil plate. So, manufacturers embossed these components and created a stencil plate for the date code portion.

        Over the past six months, two articles appeared in the Restorer with photos that describes the tire manufacturing process including both single (as your tire) and multiple stencil plates. If you think about it, as DOt cranked up its tire regulations to improve automotive safety and fuel economy it made sense for manufacturers to reduce the amount of the code they change.

        Check any tire on any car that was manufactured in the las few years and you'll see how the TIN has evolved to comply with DOT regs including the 12 alphanumberic code Jack referenced. Ironically and scary...is the format hasn't changed all that much since 1971...consumers must still dicipher the code.
        Tom Russo

        78 SA NCRS 5 Star Bowtie
        78 Pace Car L82 M21
        00 MY/TR/Conv

        Comment

        • Louis T.
          Very Frequent User
          • July 31, 2003
          • 282

          #5
          Re: Bias ply tire and DOT markings questions

          Hi Tom,

          Thanks for the excellent info. I'll pass it along to the owner who contacted me - I'll bet he'll be quite surprised to learn that he likely has '74 vintage OEM tires on his '66 as opposed to current repros. You've also peaked my curiosity about changes in the tire manufacturing process so I'll be sure to refer to the relevant articles in the recent Restorers that you mentioned.

          Regards,

          Louis

          Comment

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