Originally Posted by Dustin@Z1

The internal vane direction dictates the direction of rotation...which is what I think someone mentioned previously.

If you plan on installing brake ducts that are mounted close to the hub, you want the vanes to slant towards the rear of the car. Inside (hub edge) leading. This will allow the vane to "scoop" the air and spin it out through the middle of the disc. \\\\

If you do not plan on installing any brake ducting, then it really does not matter. However, a 19" or larger wheel will have additional clearance between the wheel's barrel and the rotor itself. These will allow air to be scooped and pulled into cool the hub/wheel bearing....in theory. ////

The vanes are designed to scoop air and force it through the rotor. The rotor will perform this action, regardless of which direction you choose. However, if you do install brake ducts in conjunction with the rotors and install the rotors in the wrong orientation, the ducting will be work to its full potential.

I hope I have answered your question.