This work develops and studies a model of an aircraft nose landing gear with torsional, lateral, and longitudinal degrees of freedom. The corresponding three modes are coupled in a nonlinear fashion via the geometry of the landing gear in the presence of a nonzero rake angle, as well as via the nonlinear tire forces. Their interplay may lead to different types of shimmy oscillations as a function of the forward velocity and the vertical force on the landing gear. Methods from nonlinear dynamics, especially numerical continuation of equilibria and periodic solutions, are used to asses how the three modes contribute to different types of shimmy dynamics. In conclusion, the longitudinal mode does not actively participate in the nose-landing-gear dynamics over the entire range of forward velocity and vertical force. Nomenclature c = longitudinal bending damping of strut c = lateral bending damping of strut c = damping coefficient of elastic tire c = torsional damping of strut e = caster length e eff = effective caster length F K = lateral tire force or cornering force F z = vertical load on the gear h = contact patch length of elastic tire I x = moment of inertia of strut with regard to x axis I y = moment of inertia of strut with regard to y axis I z = moment of inertia of strut with regard to z axis k = self-aligning coefficient of elastic tire k = longitudinal bending stiffness of strut k = lateral bending stiffness of strut k = restoring coefficient of elastic tire k = torsional stiffness of strut L = relaxation length l g = gear height M D = moment due to tire lateral damping M D = moment due to damping in the longitudinal mode M D = moment due to damping in the lateral bending mode M D = moment due to damping in the torsional mode M K = self-aligning moment due to tire force M K = moment due to stiffness in the longitudinal mode M K = moment due to stiffness in the lateral bending mode M K = moment due to stiffness in the torsional mode M = coupling moment between the tire deformation and longitudinal mode M = coupling moment between the tire deformation and lateral mode R = radius of nose wheel V = forward velocity of the aircraft m = self-aligning moment limit = longitudinal bending angle = wheel tilt or camber angle = lateral bending angle = swivel angle = rake angle = torsion angle