A wheeled vehicle includes a body frame, at least one wheel and an arm unit. A first end of the arm unit is supported by the frame body for pivotal movement about a pivot axis that extends generally horizontally and transversely. A second end of the arm unit rotatably carries the wheel. The arm unit defines an inner cavity that has first and second inner surfaces spaced apart from each other. The arm unit has a reinforcement that extends between the first and second inner surfaces.