Tires: all terrain or all season, all terrain tires, season tire

Question
is  there a difference in the sidewall design of an all season tire vs an all terrain tire and does the RMA require an AT rating on the sidewall. thank you

Answer
Tom,

There is no functional difference in the sidewall between an all season tire and an all terrain tire.

But I suspect you are asking if there is a special marking on all terrain tires that is different to all season tires.

The answer is:  No!.

All season tires can be distinguished by the letters "M" and "S" with the symbols "+", "-", "/", and several more (and if I remember correctly - no symbol at all), but there is nothing comparable for all terrain tires.

If I have this correctly, all terrain tire might considered to be a sub group of all season tires, but there is no formal definition of what consitutes this group (or sub group).