In this paper we carry out a systematic study of various ring theoretic properties of formal triangular matrix rings. Some definitive results are obtained on these rings concerning properties such as being respectively left Kasch, right mininjective, clean, potent, right PF or a ring of stable rank ≤n. The concepts of a strong left Kasch ring, a strong right mininjective ring are introduced and it is determined when the triangular matrix rings are respectively strong left Kasch or strong right mininjective. It is also proved that being strong left Kasch or strong right mininjective are Morita invariant properties.