My Vittoria Cross XGs have two arrows on the sidewall.
One direction says "speed-->" and the other says "<-- traction"
The "speed" direction has the arrows pointer forward. The "traction" direction has the arrows backwards, presumably to act as "paddles" in soft terrain. So, I have the front mounted for speed, and the rear for traction.
Does it actually make a difference? Heck if I know.