Texas allows 25% VLT (visible light transmisstion) on side windows. Non-reflective tent is allows above the AS-1 line on the windshield and the back window can be blacked out if you choose. Since 2003, anyone who applies tent, is supposed to put a decal on the driver's side window between the tint film and glass, that indicates >25% VLT and identifies the installer.
Usually HPD and most other Houston area agencies don't care and don't even know the law themselves. Every now and then however, someone flunks the attitude test and an officer will go over the vehicle looking for offenses. I saw one kid in traffic court on Lubbock street a few months back who managed to rack up at least seven citations in one traffic stop.
Cop popped him for speeding (85 in a 55) and then went on to write him up for window tint, non-DOT approved headlights, non-DOT approved signal lights, non-DOT approved taillights, failure to maintain proper height of the headlights above the ground, failure to maintain emissions equipment, failure to maintain safety equipment and the list went on. Kid ended up with convictions on all counts mainly because he wouldn't shut up. He "knew" the law just well enough to **** off the judge and had made the mistake of asking for a trial by judge rather than by jury.