[Richard and Rhonda]

You need two pieces of data to complete your investigation. The date code is one. The second is you need the Load Range of the tire. Is it a G, H, J ? You look up that load range in the table supplied on the manufacturer web site and it will tell you the inflation recommended for the load.

Those pieces of info will tell you if the tire was old, or if by mistake the coach was fitted with tires not rated to carry the load.