They indicate the results of the testing of the tyre after manufacture, and also to the import/export route the tyre is going to take after manufacture.
The exact meaning varies, there is no set "standard", each tyre manufacturer has their own markings.
They are an easy identification of the tread type during the manufacturing and assembly process.
If you mean tire tread depth, the minimum is 1.6mm.
Tread wear indicator
As a verb, tread means the way someone is walking. As a noun, tread can mean the top of a stair (where you step on), or the tread of a tire.
Stripes on the tires are just identification used by the manufacturer. Different variations in stripe width, color, and count means a certain tread goes with a certain tire.
Tread wear indicator
It sounds like the tread width in millimetres
That means it is a passenger car tire with tread width of 195 millimetres
It is an indicator of tire tread wear.
It means it is a tire for a passenger car and tread is 235mm wide.
Minimum LEGAL tire tread depth is 2/32nds of an inch.
Tire spec in PA is 2/32 of an inch of minimum tread