<p>A tractor having a chassis (10), rear axle mounting means for mounting a rigid rear axle ( 11) on the chassis for pivoting about a first axis (X-X) generally parallel to the longitudinal axis of the chassis to allow vertical movement of rear wheels carried by the rear axle, and first spring/damping means (17) acting between the rear axle and the chassis. A front axle (30) is mounted on the chassis by a front axle mounting means for pivoting about a second axis also generally parallel to the longitudinal axis of the chassis to allow vertical movement of the front wheels carried by the front axle. Second spring/damping means (33) act between the front axle and the chassis, and steering means (32) act to steer the front wheels relative to the front axle. A lock-out means may be provided to prevent pivoting of the rear axle about the first axis when desired and the rear wheels may be provided with steering means for steering the rear wheels relative to the rear axle to provide a four wheel steering capability when desired.</p>
