Catalyzes the deamimation of cytosine to uracil at position 8 of tRNA in 30 different tRNAs. This editing guarantees the proper folding and functionality of the tRNAs. cytidine(8) in tRNA + H(+) + H2O = NH4(+) + uridine(8) in tRNA Binds 1 zinc ion. Homodimer. Belongs to the cytidine and deoxycytidylate deaminase family.