The effect of various vibrational transitions on the formation of non-equilibrium distributions, rates of vibrational relaxation and chemical reactions, and fluid dynamics in CO₂ flows is discussed. Several state-resolved models are applied: The most detailed model taking into account all kinds of vibrational energy exchanges and coupling of CO₂ vibrational modes as well as reduced models with limited number of vibrational states and kinetic processes. It is shown that vibrational transitions between different CO₂ modes and between CO₂ asymmetric mode and CO molecules may significantly affect the rate of vibrational relaxation and dissociation. Whereas vibrational distributions strongly depend on the processes included to the kinetic scheme, the heat flux is practically insensitive to the vibrational kinetics and can be evaluated using simplified models.