67 Pa. Code § 179.2
It is in the public interest and promotes the public welfare to regulate the use of State highways for the purpose of moving mobile homes, oversize or overweight vehicles, and combinations of vehicles, including the loads carried thereon, in order to preserve the safety of the users of Commonwealth highways; to facilitate the movement of mobile homes, oversize or overweight vehicles, and combinations of vehicles, as well as the movement of traffic, generally; to protect the structural integrity of the highway and bridge system; and to encourage the economic growth of commerce and industry in the Commonwealth without the necessity of constant supervision by Department employes, police and local officials. Nothing contained in this chapter is intended to relax existing safety requirements.
67 Pa. Code § 179.2