I thought they only put them on DOT tires.
Just had a boo at my dirtybike and 200X. I never knew they put them on offroad tires too.
FYI. There is a 4 digit stamp on the tire from anything newer than the year 2000. If you find the stamp and it is IE. 0416. This means the tire was made the 4th week of 2016.
Have a boo at your tires. Not sure if all manufactures do this(?)