A tilting vehicle comprising: a chassis, at least one front wheel, two surface-engaging rear wheels and a propulsion unit for driving the rear wheels, each rear wheel being connected to the chassis by a wheel support assembly, the wheel support assemblies and the chassis being arranged such that the chassis, the or each front wheel and the rear wheels are operable, in use, to tilt in unison in either direction with respect to a vertical, upright position of the chassis such that the or each front wheel and each rear wheel lies in a plane parallel to the centre line of the chassis irrespective of the angle of tilt of the chassis, each wheel support assembly comprising: a rear wheel support for allowing movement of the respective rear wheel relative to the chassis, each rear wheel support and respective rear wheel being movable independently of the other rear wheel support and respective rear wheel in a plane parallel to the centre line of the chassis; and a hydraulic cylinder (144; 244), the hydraulic cylinder comprising: a housing (142; 242) connected to one of the chassis and the rear wheel support; and a piston connected to the other of the rear wheel support and the chassis, the piston being moveable within the housing and arranged to divide the hydraulic cylinder into first and second chambers (152; 154) each having respective ports arranged to allow hydraulic fluid to enter and exit the respective chamber, the ports of the first chambers of each hydraulic cylinder being in fluid communication and the ports of the second chambers of each hydraulic cylinder being in fluid communication such that movement of hydraulic fluid from the first or second chamber of one hydraulic cylinder to the respective first or second chamber of the other hydraulic cylinder displaces the pistons of the hydraulic cylinders in opposing directions relative to the respective housings (142; 242) and causes the chassis, the or each front wheel and the rear wheels to tilt with respect to the ground surface, wherein the vehicle further comprises a pump arrangement, the movement of hydraulic fluid being selectively controlled by the pump arrangement. a chassis, at least one front wheel, two surface-engaging rear wheels and a propulsion unit for driving the rear wheels, each rear wheel being connected to the chassis by a wheel support assembly, the wheel support assemblies and the chassis being arranged such that the chassis, the or each front wheel and the rear wheels are operable, in use, to tilt in unison in either direction with respect to a vertical, upright position of the chassis such that the or each front wheel and each rear wheel lies in a plane parallel to the centre line of the chassis irrespective of the angle of tilt of the chassis, each wheel support assembly comprising: a rear wheel support for allowing movement of the respective rear wheel relative to the chassis, each rear wheel support and respective rear wheel being movable independently of the other rear wheel support and respective rear wheel in a plane parallel to the centre line of the chassis; and a hydraulic cylinder (144; 244), the hydraulic cylinder comprising: a housing (142; 242) connected to one of the chassis and the rear wheel support; and a piston connected to the other of the rear wheel support and the chassis, the piston being moveable within the housing and arranged to divide the hydraulic cylinder into first and second chambers (152; 154) each having respective ports arranged to allow hydraulic fluid to enter and exit the respective chamber, a rear wheel support for allowing movement of the respective rear wheel relative to the chassis, each rear wheel support and respective rear wheel being movable independently of the other rear wheel support and respective rear wheel in a plane parallel to the centre line of the chassis; and a hydraulic cylinder (144; 244), the hydraulic cylinder comprising: a housing (142; 242) connected to one of the chassis and the rear wheel support; and a piston connected to the other of the rear wheel support and the chassis, the piston being moveable within the housing and arranged to divide the hydraulic cylinder into first and second chambers (152; 154) each having respective ports arranged to allow hydraulic fluid to enter and exit the respective chamber, a housing (142; 242) connected to one of the chassis and the rear wheel support; and a piston connected to the other of the rear wheel support and the chassis, the piston being moveable within the housing and arranged to divide the hydraulic cylinder into first and second chambers (152; 154) each having respective ports arranged to allow hydraulic fluid to enter and exit the respective chamber, the ports of the first chambers of each hydraulic cylinder being in fluid communication and the ports of the second chambers of each hydraulic cylinder being in fluid communication such that movement of hydraulic fluid from the first or second chamber of one hydraulic cylinder to the respective first or second chamber of the other hydraulic cylinder displaces the pistons of the hydraulic cylinders in opposing directions relative to the respective housings (142; 242) and causes the chassis, the or each front wheel and the rear wheels to tilt with respect to the ground surface, wherein the vehicle further comprises a pump arrangement, the movement of hydraulic fluid being selectively controlled by the pump arrangement.