Ohio Rev. Code § 5577.09
All rules as provided by section 5577.08 of the Revised Code shall be made by the board of county commissioners, at regular meetings, by a majority vote. Such rules shall be kept on file in the office of the board and open for inspection by the public.
At least two days before such rules become effective the board shall cause to be placed and retained on county and township highways classified under section 5577.08 of the Revised Code or sections thereof, and on any bridge classified under section 5577.08 of the Revised Code, at both ends and at any points of intersection, signs, of substantial construction, which will conspicuously indicate the limitations of weight of vehicle and load or speed which will be allowed on such highways or bridges.
It shall be unlawful to operate upon such highway or bridge a vehicle whose maximum weight or speed is in excess of the limitations prescribed. The expense of the purchase and erection of signs provided for in this section shall be paid from the county funds for the maintenance and repair of highways, bridges, and culverts.
R.C. §5577.09