A method for determining a lateral mode stiffness of one or more fluid tubes (103A, 103B) in a vibrating meter (5) is provided. The method comprises a step of vibrating at least one of the one or more fluid tubes (103A, 103B) in a drive mode vibration. Drive mode sensor signals (310) are received based on a vibrational response to the drive mode vibration. At least one of the one or more fluid tubes (103A, 103B) is vibrated in a lateral mode vibration, wherein the lateral mode is approximately perpendicular to the drive mode. Lateral mode sensor signals (317) are received based on a vibrational response to the lateral mode vibrations. The method further comprises determining a lateral mode stiffness (318) based on the lateral mode sensor signals (317).