Ohio Rev. Code § 1327.59: Presumptions.

Proof of the existence of a weight or measure or a weighing or measuring device in or about any building, enclosure, stand, or vehicle in which or from which it is shown that buying or selling is commonly carried on creates a rebuttable presumption of the use of such weight or measure or device for commercial purposes and of such use by the person in charge of such building, enclosure, stand, or vehicle.