Motorcycle Repair: Brake rotors, brake rotor, inner radius

Question
I'm confused about how thick my rotors should be. I have 1987 gl1200I Goldwing. I see some information that says my front rotors should be a minimum of 4mm and others that say 9mm. Why the discrepency? What should the minimum of the rear rotor be as well?

Answer
Some goldwings have vented brakes, some don't.  The vented rotors are thicker.

OK so because I'm dealing with a) people who insist on NOT reading my instructions before answering questions, and STILL ask me things about something else.  or b) idiots. (you pick the category in which you fall...)  My fault i guess; I still try to occasionally help the questioners.  I should know better.

But just for you, Steve, I'll spell it out.  CLEAN your brake rotors.  READ on the inner radius, and ON YOUR OWN BRAKE ROTOR, it will SPELL it out for you:  "Minimum Thickness X mm".  for non vented rotors this will be 4mm, and for vented rotors it will be 9mm.

Hope this is clear enough for you,  Jan