how are you meant to measure light reduction?back 3 can be as dark as you like.
Windscreen is a no no
front 2 have to let at least 70% of light through which basically means you cant tint them as they let 70/80% though from factory.
The windscreen can be tinted, it has to let through atleast 75% light though^ ditto what he said.
pretty much any window to a certain degree but no way the front widnscreen