Vehicle drivers receive haptic feedback in response to their movement of the steering wheel and tactile feedback from various sources of vibration of the steering wheel, with the sensations varying depending on the frequency and the magnitude of the movements. From an experiment with 12 subjects, equivalent comfort contours were determined for vertical vibration of the hands with three grip forces. The perceived intensity of vibration on a rigid steering wheel was determined using the method of magnitude estimation at seven frequencies (4 to 250 Hz) over a range of vibration magnitudes (0.1 to 1.58 ms-2 r.m.s). The comfort contours strongly depended on vibration magnitude, indicating that a frequency weighting for predicting sensation should be dependent on vibration magnitude. At low magnitudes, increased grip force increased sensitivity at high frequencies and enhanced the frequency-dependence of the equivalent comfort contours. The results may be explained by the characteristics of the Pacinian and non-Pacinian tactile channels in the glabrous skin of the hand.