I agree with Rick, the four digits do not conform to the date code system in affect since the year 2000. I would suspect these tires to be older than 2000 and use them at your own risk. The rubber hardens as it ages. The coefficient of drag reduces as the tire ages. There is also the problem with the inner tube being old. Years ago the spare tire on my truck exploded for no other reason than being old. Of course it was of tubeless design, but it threw about 7 inches of belt. We also lost a tire on an aircraft cargo loader at work. Same thing, it was a truck tire over 20 years old and it exploded in the same fashion.