Go to your local motorcycle dealership, Honda, Kawasaki, Yamaha, etc. Ask to see their Parts Unlimited Catalog (also available free from them on CD). Look up the size and brand tires you want and order right there at the dealership. Their prices are CHEAP, and you don't have to pay shipping!
You will have your tires in hand within 3-5 days. It's that simple. Go anywhere else and I guarantee you will pay more and have to pay shipping on top of the inflated prices. Listen to me, I do it all the time. No better way to buy tires for your moped.....period.