Sting-Ray Slick Tire 20″ x 2.125 Originally used on the extra cool late 60s Schwinn Sting-Ray, Krates or Muscle Bikes. Nostalgia whitewall tire for the ultimate old school look! 20 x 2.125 57 x 406 This tire fits on all 20″ Classic Cycle rims up to 57 mm (~2,24 inches) width! But please check frame/fork for clearance! If you assemble the tire on wide rims not to put more pressure than 16 PSI. It could blast.