Rear rotor.

I will repeat in more straightforward language.  When replacing parts with non OEM stuff, unless one has the calculations (and understand them) that the OEM engineers made to decide on various components it is best to stick to OEM.  I don't have the calcs, although if I did, as a mechanical engineer I think I would understand the thought process behind them.  Therefore I would always recommend sticking with OEM specs, and that's why I wrote my original comment that Wookie disagreed with. 

Wookie, when you become a mechanical engineer you can argue that point with me.  Until then stick to electrical.  As for your own bike...you're free to do whatever you wish.  It's your life and your dime.

I think we need to "agree to disagree" on this one and move on - you are right in that I'm not a mechanical engineer and I don't want to "fall out" with anyone over a difference of opinion