Ohio Rev. Code § 5577.08
The board of county commissioners may classify the county and township roads and bridges and all other roads and bridges within their respective counties, except state highways and bridges on state highways, with reference to the maximum weights and speeds permitted on such roads and bridges.
The classifications made by the board under this section shall not apply to vehicles of a weight of five tons or less for vehicle and load.
In making the classifications, the board shall take into consideration the nature of the roadbed, construction, and any other factors which are material in the proper classification of such roads and bridges.
The board shall make rules governing the weight of vehicle and load and the speed permitted on the several classes of roads and bridges.
R.C. §5577.08