75 Pa.C.S. § 4906: Fire apparatus and emergency vehicles.

This chapter does not apply to fire apparatus being operated on the highway unless specifically provided otherwise. The weight requirements of this chapter do not apply to emergency vehicles as defined in 23 U.S.C. § 127(r)(2) (relating to vehicle weight limitations-Interstate System). In lieu of the weight requirements of this chapter, the requirements of 23 U.S.C. § 127(r)(1) shall apply to emergency vehicles.