I just bought a new 2013 Super8 150 and they now come stock with a 120/70 R14 front tire so you can probably go with this size which is widely available . Try these: Avon AM63 Viper Stryke , Michelin City Grip Scooter Tires, Michelin Gold Standard Scooter Tires, Pirelli Diablo Scooter tires, Shinko SR567.
I think the bigger problem would be finding a REAR tire in the correct 120/80 - 14 size. All of the tires I've seen of this size are FRONT tires, not rear(there is a difference).