Ohio Revised Code Title XLV. Motor Vehicles Aeronautics Watercraft § 4503.08

(A) The weight of all motor vehicles, except those taxed under sections 4503.042 and 4503.65 of the Revised Code, shall be the weight of the vehicle fully equipped as determined on a standard scale. The weight of any machinery mounted upon or affixed to a motor vehicle and not inherently motor vehicle equipment shall not be included in the determination of the total weight.

(B) The horsepower of all vehicles propelled by internal combustion engines shall be computed upon the following formula: square the diameter of the cylinder measured in inches, multiply by the number of cylinders, and divide by two and one half. For all motor vehicles propelled by steam engines, the rating of the horsepower shall be based on the system of rating adopted by the United States government.

(C) For all motor vehicles propelled by electricity, the rating of the horsepower shall be the normal horsepower of the electric motor therein, to be ascertained by the registrar of motor vehicles.