Expressions for the coupled mechanical vibrations and electrical admittance of ferroelectric tubes having transverse isotropy are derived and the results supported with experimental data. Coupled modes in radially polarized barium titanate tubes are examined as a function of length to radius ratio. A frequency-dependent expression is given for the admittance in terms of electromechanical coupling, capacitance, and tube length. Results permit close prediction of resonant frequencies. An optimum length to radius ratio of 2.9 is indicated for maximum electromechanical coupling with the gravest radial mode in a radially polarized tube.