I know Goodyear moved the red stripe inward on speedway after 1967. Firestone as you state may have been in 66ish as you state.

Firestone red stripe
 

The F70 Wide Oval was introduced for the 1967 model year. In this image the top tire is the '67 only version, which is what the OP has. The bottom tire is the '68 version with the stripe moved closer to the bead. The '68 version may have came on some very late '67s and was offered as a warranty replacement of '67s due to sidewall issues. Note that the lettering on both of these is on the inside of the stripe unlike the '69 and later version, which are the same as the repop tires.

Bill W

----66 or earlier would have been a 7.75. To my knowledge no GM car had an f-70 until 67. I am mildly surprised that the tire is a 68 although I agree. I sort of thought they changed the stripe location sometime in late 67......Bill S

I had a couple ask about the tread. Here are some pics. Sorry for the delay, Im in the process of moving so it's been very hectic.

As Bill noted, that is the 67-only version. The stripe was moved as shown on the second tire in Bill's pic some time in latter 67 production, and definitely before July of 1967. Then that version was used on 68's as well. Then a completely new sidewall (with the writing on the outer portion of the sidewall and stripe close to the wheel) came along for 69 and is what has been repopped.

And that is not a 1968 (or 1978 or 1988) date code. The standardized dating did not come along until well after this tire was made. The Firestone codes from this vintage are undecipherable and as far as I know no one has the info to decode them. Several years ago I engaged in lengthy discussions with Firestone over several weeks to see if they still had that data and could track it down, and it was a dead end.

By contrast, even though Goodyear also had a cryptic system back at that time, the key to decode it is known and it is very easy to determine the mfr. date of a pre-DOT Goodyear tire.