Wis. Stat. § 194.11: Inspection of premises or vehicles.

The department or its duly authorized agents may at any time enter upon any premises within this state occupied by any common motor carrier of property or passengers, any contract motor carrier or any private motor carriers, or any motor vehicle of a common motor carrier, contract motor carrier or a private motor carrier for the purpose of exercising any power provided for in this chapter. Duly authorized agents of the department may stop a motor vehicle under this section upon the public highways for the purpose of exercising any power provided for in this chapter.