1970 Z28 Bias Plys

Discussion in '1970 - 1973 Specific' started by gpm6367, Jul 25, 2019.

  1. gpm6367

    gpm6367 Veteran Member Gold Member

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    AD20A0B1-A648-40AA-B1E5-808B59FC622F.jpeg I know that original tires are F60x15 and the consensus is that the Goodyear Polyglas GTs have the tire size in raised white letters/numbers on sidewall. The Kelsey Tire website says they were used exclusively after 1/1/70.

    My spare is original and does not contain the tire size on sidewall. I am torn between getting a matching set to the spare or a set with the tires size on sidewall.

    What are the odds that originally the spare would not match the tires on the car?

    Anyone ever seen this tire used on a 1970?
     
  2. Gary S

    Gary S Administrator Lifetime Gold Member

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    All 5 tires would have been purchased and installed at the same time so if that tire is original, you can bet that the other 4 would be the same.
     
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  3. x77-69z28

    x77-69z28 Veteran Member

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    What is the date code on the tire compared to the production date of the car. My car is an 04D van Nuys car, and the spare has the tire size
     
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  4. gpm6367

    gpm6367 Veteran Member Gold Member

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    A2126D06-A8F3-4F7C-A7C7-A8998BBB29CD.jpeg
    The car is 06D the spare rim is 5-28-70 (13/16 stem opening) and tire, if I decoded correctly, is a series 2 dated May 1969.

    Interestingly someone pointed out that my spare is marked as a blemish. Could GM have bought a bargain lot of blemish tires and used them for spares?
     
  5. 70lt1z28

    70lt1z28 Veteran Member Gold Member

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    I don't believe GM would have legally been allowed to use blems on the line, even for a spare. I know back then blems were just a cosmetic thing but I would have been surprised they would do it. Lots of bad PR if folks discovered it.
     
  6. COPO

    COPO Veteran Member Lifetime Gold Member

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    I 2nd on that, that GM wouldn't be caught dead using a blemished tire. They wouldn't even use a blemished battery cause back in the early 80's, GM sold blemished batteries to GM employees for $40 a pop because they didn't allow them in a production vehicle.

    If your going with bias tires then you want this lettering.
    [​IMG]

    [​IMG]
     
  7. mallard

    mallard Veteran Member

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    I was in the motor vehicle mechanical repair trade for most of the 70s-early 80s & we were always told the roundest most cosmetically presentable tires were set aside for new vehicles. Very lucrative supply contracts for the tire companies no doubt.
     
  8. ACF

    ACF Member

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    Because your spare tire is dated an entire year before your wheel and car dates, I would think it's from another vehicle and not original to your car. I believe the no size on the sidewall is what was used on Boss Mustangs. I've never seen these Polyglas (without tire size) used on an original 1970-71 Z28.
     
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  9. gpm6367

    gpm6367 Veteran Member Gold Member

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    Ever check the date on a “new” tire when it’s sold to you? Tire production is done in quantity and I would be willing to guess many “new” tires are not dated within 6 months of their sale.

    COPO is that your original spare? Anybody have a known original spare in their car? If so what is date on spare and what is date of car’s assembly?
     
  10. COPO

    COPO Veteran Member Lifetime Gold Member

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    No, that is not my orig spare.
     
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