To date a tyre, first find the code DOT then some letters/numbers then in an oval four digits, in the photograph DOT 4TM9 YAM1 (3513) this indicates the tyre is 2013 tyre. This will be easy to find if the tyre has been properly fitted with the DOT markings on the outside! If your tyres are over 5 years old then they will likely perish, let water in and the steel bands will break causing the fault in the previous pictures. The best outcome is vibration and a tyre change, the worst outcome is a blowout and an upside down flying fifteen!
Keith Jamieson
The Flying Fifteen Blog 