Chevrolet SS wheel spare tire question

[jeffschevelle]

I'm late to the party. First, I see nothing that suggests that that tire is not an original 1969 tire. Tread is consistent with the 1969 Firestone tread layout, which is what Coker and others have used as the repro. 67 model year to mid 68 Wide Oval is the version that is not reproduced.

Second, not all DOT marked tires have a standardized DOT date code. The initial DOT marking requirements were only to have "DOT" and a manufacturer's code. The standardized DOT date coding requirement came along later.

Third, there is no way (not that anyone has shared at least) to decode the numeric codes on Firestones before standardized DOT date coding became required.

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Regarding the start date of DOT markings, I spent many hours about a year ago finding and then reading the entire "National Traffic and Motor Vehicle Safety Act of 1966", and every single one of the DOT tire markings regulations that were issued from 1967 through the early 70's. I even did a spreadsheet with the timeline of what markings were required and when!

The only bright line rule is that any tire made on or after 8/1/1968 was required to have the "permanent" molded in DOT marking. But that does not mean that some tires made before then didn't have the DOT marking. And I have seen irrefutable evidence that the start date for the DOT marking varied by tire manufacturer, and sometimes even by tire model from the same manufacturer. When the DOT statutes were adopted, and the regulations then issued, the mandatory start date for including the DOT marking was later, and then the deadline was pushed off a couple times so as to give the manufacturers time to comply. And even when the rules finally became effective stickers and tags were allowed to be affixed to tires (in lieu of molded in data) for a period of time to allow even more time for mold alteration.

But some of the manufacturers were able to be compliant well before the deadline, with altered molds, so they went ahead and added the markings before the deadline. Same for anyone making a brand new tire design in between the initial regs and the deadline - it would have made no sense not to go ahead and include the markings in the new molds rather than omitting them first and then having to change them again before the deadline.

That's a long winded way of saying there is no hard and fast date for when the DOT marking actually began for a given tire mfr. (other than all tires made on or after 8/1/1968 should have it). But below is a summary of Tire marking regs timeline to give you some guideposts:

9/9/66 - Effective date of "National Traffic and Motor Vehicle Safety Act of 1966". Tire regs were required to be issued on or before 9/9/68.

7/22/67 - Proposed tire regs issued, with initial proposed effective date of 1/1/68 (later extended - see below).

10/14/67 - Additional tire regs issued.

11/16/67 - Final tire regs issued requiring DOT mark (effective dates and deadlines below).

12/15/67 - Tire marking requirements were amended, effective 1/14/68. Deadlines did not change. (Note that on 4/11/68 and 5/29/68 the Tire regs were amended again, effective immediately, but the markings requirements were not changed by those amendments, so they did not change any of the markings deadlines below.)

1/1/68 - Effective date of all the 11/16/67 + 12/15/67 Regs, EXCEPT:

- 4/1/68 - Effective date of tire markings requirements, EXCEPT:

--- 8/1/68 - Deadline for tire mfrs to comply with "molded in" permanent tire marking reqts (affixed stickers or tags were allowed to be used from 1/1/68 - 7/31/68).

Cheers!