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.
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) . . .????