How to tell the age of an agricultural tyre
Every tyre has a DOT code (sometimes called a date code) which indicates the date the tyre was manufactured. This is normally a 4 number code stamped into the sidewall of the tyre.
How to read the code
The code normally looks something like the following:
The first two numbers indicate the week the tyre was manufactured in (i.e. 22nd week)
The second two numbers are the year the tyre was manufactured in (i.e. 21= 2021)
Therefore, in this example, the tyre was manufactured in the 22nd week of 2021.
How to find the code
The DOT code is normally stamped into the sidewall of the tyre within an oval or pill shaped indent. It is usually only stamped on one side of the tyre.
BKT tyres sometimes have a B at the beginning and indents from the screws that hold the number to the stamp.
As agricultural tyres aren’t as fast moving as car tyres, it is quite normal for agricultural tyres to be a few years old. Tyres will often be stored at the manufacturers warehouses for a number of months even before coming to the UK.
More examples are as follows:
42nd week of 2018 
5th week of 2021. BKT DOT code, which has the B at the beginning and two screw imprints. 
16th week of 2021 
46th week of 2019