simsurfer, the law for there is:
No tint is allowed on the windshield.
Front Side Windows Must allow more than 70% of light in.
Back Side Windows Must allow more than 70% of light in.
Rear Window Must allow more than 70% of light in.
Front Side Windows No metallic or mirrored appearance.
Back Side Windows No metallic or mirrored appearance.
Restricted Colors No colors of tint are explicitly banned.
Side Mirrors Dual side mirrors are required if back window is tinted.
Certificate Requirements Manufacturers of film do NOT need to certify the film they sell in the state.
Sticker Requirements
Medical Exemption State allows medical exemptions for special tint. For more details about the specific terms of the exemption, consult your state law.

http://www.tintcenter.com/laws/PA/