Ohio Rev. Code § 5555.48
The proportion of the compensation, damages, and expenses of the improvement to be paid by the county shall be paid out of any road improvement fund available therefor.
For the purpose of providing by taxation a fund for the payment of the county's proportion of the compensation, damages, and expenses of constructing, reconstructing, improving, maintaining, and repairing roads under sections 5555.01 to 5555.72, inclusive, of the Revised Code, the board of county commissioners may levy annually a tax not exceeding two mills upon each dollar of the taxable property of the county. Said levy shall be in addition to all other levies authorized by law for county purposes, and subject only to the limitation on the combined maximum rate for all taxes.
R.C. §5555.48