Here are the sections of the PA Motor Vehicle Code and the Motor Vehicle Inspection Regulations dealing with sun screening products.
Note that only sunscreening "which does not permit a person to see or view the inside of the vehicle" is prohibited.
If (e) (1) really prohibited all sun screening, then even out of state drivers who complied with all State and Federal Laws would be prohibited from driving in PA. If the Federal Government and other States permits something related to interstate commerce, PA cannot restrict it in that manner.
The Inspection Regulations, in accordance with the Vehicle Code, do not prohibit sun-screening unless it is non-transparent, meaning you cannot see through it.
Although the term transparent might seem vague, the Regulations in Appendix C further define Reflectance and Transmittance, and permit sun screening with a reflectance of 35% or less.
(e) Sun screening and other materials prohibited.
(1) No person shall drive any motor vehicle with any sun screening device or other material which does not permit a person to see or view the inside of the vehicle through the windshield, side wing or side window of the vehicle.
(2) This subsection does not apply to:
(i) A vehicle which is equipped with tinted windows of the type and specification that were installed by the manufacturer of the vehicle or to any hearse, ambulance, government vehicle or any other vehicle for which a currently valid certificate of exemption has been issued in accordance with regulations adopted by the department.
(ii) A vehicle which is equipped with tinted windows, sun screening devices or other materials which comply with all applicable Federal regulations and for which a currently valid certificate of exemption for medical reasons has been issued in accordance with regulations adopted by the department.
(3) A certificate of exemption shall be issued by the department for a vehicle which is:
(i) Registered in this Commonwealth on the effective date of this subsection and is equipped with a sun screening device or other material prohibited under paragraph (I) on the effective date.
(ii) Equipped with tinted windows, sun screening devices or other materials for a physical condition that makes it necessary to equip the motor vehicle with sun screening material which would be of a light transmittance or luminous reflectance in violation of this section.
(A) A certificate of exemption for medical reasons shall be issued only if the owner or registrant of the vehicle, or a person residing in the household of the owner or registrant who regularly drives or is driven in the vehicle, suffers from a physical condition deter-mined by the department, in consultation with the Medical Advisory Board, to justify the exemption.
(B) Any person requesting an exemption for medical reasons shall have his physical condition certified to the department by a licensed physician or optometrist.
(4) A certificate of exemption issued under this subsection shall be carried in the vehicle and displayed on request of a police officer.
(5) Upon the sale or transfer of the vehicle to any person who does not qualify under paragraph (2)(ii), the exemption shall be null and void. Prior to the sale or transfer of an exempt vehicle, it shall be the sole responsibility of !he owner or seller of a formerly exempt vehicle to remove all sun screening or other materials from the vehicle. At the time of the sale or transfer of a formerly exempt vehicle, the owner shall remove and destroy the certificate of exemption for physical reasons and provide the purchaser with a notarized statement setting forth the name and address of the owner or seller, the vehicle identification number, year and model, and the business entity and process used to remove the sun screening or other material.
(2) Check glazing.
(i) Check glazing and REJECT IF any of the following apply:
(A) Approved safety glazing is not used in every windshield, window or wing.
(B) Any sign, poster or other non-transparent material obstructs, obscures or impairs driver's clear view of highway or any intersecting highway. See Appendix C.
(C) Non-transparent material extends more than 3 inches from lowest exposed portion of rear window, rear side windows or rear wings. See Appendix C.
(D) Motor vehicle has any sign, poster or other non-transparent material on windshield or front side windows, other than officially approved and properly located parking stickers.
(E) Glass is shattered or broken or has any exposed sharp edges.
(F) Windshield is removed.
(G) There are any defects in acute area of windshield,-center of critical area on driver's side of vehicle directly in driver's normal line of vision, 8 _ inches wide and 5 1/2 inches high-or discolorations or hazardous cracks to front, right, left, or rear of driver which would interfere with driver's vision. See Appendix C.
(H) Class etchings, except those used for identification, are on windshield or front side windows.
(I) Glass etchings extend more than 3 inches