Tire date code help?

[Verne_Frantz]

I'm trying to figure out the date of manufacture of a spare tire found in a '61 Impala. The tire reads:
7.50-14 safety 800. US Royal

Spare also says low profile tubeless. 1207-154 AA 686. 4 ply rating 2 ply. 20XD4


Any help would be appreciated. Although the size is correct, I have a hunch it's not the original spare. The wheel shows signs of being mounted and the tire has wear.



Thanks
Verne
165284

[Lee Stewart]

I can help a little . . . The Safety 800 was the "brand" US Royal sold to car manufacturers. For 1962 models they came out with a new compound called CVC: Catalytic Vulcanizing Compound which stopped tire failures and increased tire life.

https://i.postimg.cc/7PF0nzLZ/0-0-2737-3503.jpg (https://postimages.org/)

Tire codes back then were not uniform. Each manufacturer had his own code. Not until the DOT made them in 1971. Date codes were usually 4 digit numbers: 1st 2 digits were the week the tire was made, 2nd 2 was the year the tire was made. I don't see 4 digits. I see three (686) and I see 5 (20XD4) . . .????

[Verne_Frantz]

That's a good reference Lee. Thanks. I understand now that prior to the DOT mandate (which I thought was 1968) each manufacturer had their own dating methods. Since US Royal is out of business, I doubt I'll be able to decode the date.
Let's just suppose the 1207 indicates (1) the year, 1961, and 207 is the day of the year. That would make the manufacture date the 4th week of July, which just happens to be the week this car was built!
This tire also says low profile tubeless. 4 ply rating 2 ply.


Verne