Asymetrical tireshy, My mistake? Options

[BMXerror]

Hey all. I ordered some Khumo Escta ASXs to replace the rotted out Dunlops on my Porsche. I had them mounted and balanced at the local shop, but a couple days later, I noticed something. They're asymetrical, which I knew, but I didn't realize that that means the tread points forward on one side, and backwards on the other. I looked at the sidewalls and the 'outside' markings are on the outside all the way around. Do you have to buy right and left side tires when you go with and asymetrical design? It sounds to me like a stupid question, but I don't know if it'll do well in wet weather with one side pushing the rainwater forward under the tire. They are an all season tire afterall. Any info would help. Thanks
Mark D.