What is the allowable minimum depth of the thread in a tire not fitted with a tire indicator bar.

Why?

If a tyre has no tread wear indicator, the minimum permitted tread depth is 1.6 mm. A tyre worn below this limit must not be used. The values of 2.6 mm and 3 mm are higher, but neither is the legal minimum.

§ 11 ust. 7 pkt 4 rozporządzenia w sprawie warunków technicznych pojazdów oraz zakresu ich niezbędnego wyposażenia