You can know the manufacturing date of a tyre through the DOT number printed on the sidewall of the tyre. The last four digits of the DOT tells us about the date of manufacturing. For example, let's assume that the last four digits of DOT printed on your tyre sidewall are- 4512
45 12 means the tyre was made in the 45th week of 2012. Similarly, if the last four digits were 4906 , it means tyre was made in the 49th week of 2006.