A good linear correlation is found between the four-point charge radius relation δR2p−2n(Z, N ) with that of quadrupole deformation data in even-even nuclei. This results in a further improved charge radius relation that holds in a precision of about 5×10 −3 fm. The new relation can be generalized to the reduced electric quadrupole transition probability B(E2) between the first 2 + state and the 0 + ground state, and the mean lifetime τ of the first 2 + state. Same correlations are also seen in global nuclear models, their precisions, however, are not enough to be consistent with the experimental data.