Presented in this work are 102 vapor phase PvT measurements for blends of trans-1,3,3,3-tetrafluoroprop-1-ene (R1234ze(E)) + methane and 85 vapor phase PvT measurements for blends of R1234ze(E) + nitrogen. The R1234ze(E) + methane data consist of eight data sets measured along five isochores (0.12, 0.09, 0.06, 0.04, and 0.03) m(3 center dot)kg(-1) for (267 < T < 413) K. The blends consisted of four methane mole fractions (0.25, 0.31, 0.50, and 0.75) mol.mol(-1). The R1234ze(E) + nitrogen data consist of six data sets measured along three isochores (0.07, 0.11, and 0.14) m(3 center dot)kg(-1) for (263 < T < 413) K. The blends consisted of three nitrogen mole fractions (0.25, 0.50, and 0.75) mol.mol(-1).