Tir is the fourth month of the Zoroastrian calendar. As with all Zoroastrian months it is thirty days long. It is dedicated to Tishtar, the yazad of the star Sirius and the pre-harvest rains. Tishtar is especially celebrated on the thirteenth day of the month, in Jashan-e Tiragan. This always falls in the middle of the festival of Maidyoshahem, which runs from the eleventh to the fifteenth of the month.
The three different versions of the Zorastrian calendar are aligned differently with the Gregorian calendar. Therefore, Tir falls at a different time in the natural year on each calendar. These dates are: