The influence of the substitution of Zr⁴⁺ by oversized rare-earth R³⁺ (R ≈ Sc, Yb, Y, Gd, Sm) was investigated in nanocrystalline tetragonal R₂O₃-doped zirconia (ZrO₂) ceramics. Three batches of samples were investigated as a function of various contents of oversized trivalent dopants, i.e., (i) scandia and (ii) ytterbia, and as a function of different dopant ionic radii, for a constant R₂O₃ content of 3 mol %. Quantification of internal pressure was performed from frequency shifts of Raman spectra and from compressibility data from XRD.