Abstract: A safety arrangement in a motor vehicle comprises a seat to be occupied by a passenger of the vehicle. The seat is supported by a framework (32, 33). The framework is mounted on to a carriage (6) by four deformable members (5) each having sensor means responsive to deformation of the deformable members. The sensor can determine the weight of a person sitting on the seat and also the position of that person within the seat. The sensors are associated with controls adapted to initiate and control the inflation of an air-bag when an accident arises. The inflation characteristic of the air-bag can therefore be adapted to the weight and position of the occupant of the seat.