Originally Posted by
GSRRacer95
It would be 30%, not 70%. It has to allow 70% of the light in..
the %'s on tint work the other way around
EDIT:
The number you will most commonly see is the VLT% (Visible Light Transmittance). Almost all the official names of films include the VLT% within it like Johnson Executive PBC30 or Madico Charcool CH-55. VLT% tells you how much visible light is allowed to shine into the car, and also indirectly how dark the tint looks.
http://www.tintcenter.com/articles/bt_works.html