OAR 734-082-0010: Tires

(1) The permitted vehicles must be equipped with tires of sufficient size so the gross weight on any wheel, axle, tandem axle, or group of axles does not exceed 600 pounds per inch of tire width, except as provided in section (2) of this rule. (2) By single-trip permit, unladen self-propelled vehicles, equipped with low pressure flotation tires (15-inch or larger) may be permitted 700 pounds per inch of tire width to a maximum of 36,000 pounds on any single axle or 43,000 pounds on any tandem axle. (3) In no instance shall the weight carried on a tire exceed the manufacturer's sidewall tire rating. (4) A motor carrier transporting a single non-divisible permitted load that exceeds the weight limits allowed by ORS 818.010 may carry spare tires with or without wheels for the transporting equipment, and if transporting a vehicle, no more than one spare tire with or without wheel of each size used by the transported vehicle. The single non-divisible permitted load shall comply with the following dimensions: (a) The width does not exceed eight feet six inches due to items loaded side by side or overlapping; (b) The height does not exceed 14 feet due to items stacked one on the other; and (c) The weight does not exceed that authorized by permit.