The first two numbers represent the week of the year, while the last two numbers represent the year. For example, a TIN ending with "1219" indicates that the tire was manufactured in the 12th week of 2019.
It's important to note that the TIN only indicates the week and year the tire was manufactured, not when it was installed on a vehicle. Tires should be replaced after six years, regardless of how much tread is left, so knowing the age of your tires is important for safety.