There was a thread on this very forum around 10 years ago where this issue was extensively ventilated. The OP had a tyre or 2 fail on ax Xplorer if I remember correctly. In that case the tyres were (only) ten years old and we had some feedback from someone in the know that tyre manufacturers consider the expiry date on their product to be 5 years from that very same little 4-digit stamp on the sidewall.
Very few knew about it then, and since then a new generation of owners has grown up without that knowledge. I urge every caravan owner to go out ASAP and check the manufacture date on their caravan if it is more than 5 years old.
I also now always check the manufacture date on replacement tyres for my cars and I’ve caught them trying to sell me tyres that have been lying in the store for 3 years or more.