Super Tires 1501S Silicone tires for ReveSlot Porsche and Marcos. Super Tires 1502S Silicone Urethane Tires for ReveSlot Porsche, Viper, Supra. Super Tires 1502U Urethane Tires for ReveSlot Porsche(2nd release with wider rims like on the Viper), Viper, Supra. These are new molds and the tires fit flush with the rim. Super Tires 1501U Urethane