Every motor carrier subject to the provisions of this chapter shall file with the commission, and keep open to public inspection, schedules showing all the rates and charges for service to be rendered by it or by other persons in connection with it: Provided, however, That the reports and tariffs filed by an interstate motor carrier with the commission may be copies of its reports and tariffs filed with the interstate commerce commission, but nothing herein shall preclude the commission from requiring interstate motor carriers to furnish information bearing upon any complaint or question before said commission and with which it has a right to deal.