(1) The lower radius rods on the rear axle do not have sufficient strength, and therefore they may crack if the vehicle is repeatedly driven on a curvy road at a low speed, such as on a mountainous road. If the vehicle continues to be driven with such a cracked radius rod, the rod may break, which would adversely affect the stability of the vehicle. (2) The lower radius rods on the front axle do not have sufficient strength for unanticipated lengthy use, and therefore they may crack. If the vehicle continues to be driven with such a cracked radius rod, the rod may break, which would adversely affect the stability of the vehicle.