That was quick, what did you order?
I run 42/42 psi (Commander II on the rear and that rear BT45 on the front). I've tried that BT45 mounted in both directions. I can't tell a difference, wet or dry, and mileage is good for either direction. Like car tires, opinions are strong either way regarding direction of mounting... flip a coin. Personally, for our type of riding on our type of bike, I don't think it matters much.