unsure how true this is iv been told by a copper and my insurance you r allowed 2 have as dark as u want on back 3 even painted, but it is illeagal 2 have anything infront of the b post ( this includes the lil triangles on ours) but u are allowed up 2 a 6" sunstrip in up 2 medium smokeThe law states that front side windows must let => 70% of light pass through them, the Windscreen has to let => 75% through and theres NO limit for windows backwards of the B pillar.
Please remeber that most cars already have lightly tinted glass.
Lothian and borders police only had one light meter at the start of 2006, but I am led to believe they have purchased a few more now! And most VOSA inspectors carry them.
http://www.vosa.gov.uk/vosacorp/repository/Tinted Windows Nov 2005.pdf
i have been stopped by vosa a few years ago for my tints and he told me that you cant put anything on your front windows or you would make them illegal mate
probbs both truAs I understood the law, the front side windows must let at least 70% light through but in reality, as all windows have a light tint built in, any tint film applied is likely to take the level over the limit.