The free vibrations of three pneumatic radial tires for passenger cars were predicted using a nonlinear, laminated thin shell of revolution finite element (FEM). Of particular interest are those meridionally symmetrical and radially vibrating modes of tires. Frequency measurements were conducted and compared with the predictions. One of the FEM tire models was used to investigate the effects of inflation pressure, ply cord modulus, ply cord end count, ply compound modulus, belt angle, and belt end count to the tire's natural frequencies. In addition, the frequency response functions of these three tires were predicted, using their predicted natural frequencies and mode-shapes, and compared with the measured results.