(4)Tachographs should be installed in vehicles to which Regulation (EC) No 561/2006 applies. Certain vehicles should be excluded from the scope of that Regulation in order to introduce some flexibility, namely vehicles with a maximum permissible mass not exceeding 7,5 tonnes used for carrying materials, equipment or machinery for the driver’s use in the course of his work, and which are used only within a 100 km radius from the base of the undertaking, on condition that driving such vehicles does not constitute the driver’s main activity. In order to ensure coherence between the relevant exemptions set out in Regulation (EC) No 561/2006, and to reduce the administrative burden on transport undertakings whilst respecting the objectives of that Regulation, certain maximum permissible distances set out in those exemptions should be revised.