Universal tint level for windows

[Harmonica]

I'm fixing to get the windows tinted on my car so I don't have to mess with curtains, and to generally keep the interior cooled off most of the time. I'm looking here to see the laws on window tint. 

http://drivinglaws.aaa.com/tag/glass-window-tinting/

I'm planning to spend most of my time in Texas, New Mexico, Colorado, Utah, Wyoming, and California. It looks like, not counting the windshield, the minimum is they need to allow at minimum 30% light transmittance. So I think I'm gonna go with that amount. It looks like some reflection is allowed too but I'm not sure if that affects the transmittance number.

I have to admit, I'm a little surprised that so many people utilize curtains for their car instead of tint. Am I missing something? Has anyone ever had troubles with a cop citing them for too much tint? What happened?

 

[Almost There]

Tint levels are state regulated so what you're allowed will depend on the state you are titled in. Tint levels differ for driving compartment windows and rear windows. Some people have been hassled when pulled over in a state that allows less tinting than their registered state but most often aren't cited because they are complying with their home state.

The reason most people use curtains instead of tinting is that short of a 100% tint, even the darkest tints allow SOME light to come through from the inside to the outside. Blackout curtains are also much cheaper than tinting the windows and then still having a problem with light transmission. Even with the back windows darkly tinted you're still going to need curtains for the windshield unless you have a minivan where you're only concealing the back portion of the vehicle and leaving the driving compartment open to viewing.