The Santa Cruz Slime Balls Guts Speed Balls Skateboard Wheels shaped skateboarding from the early days to what it is today and their original wheels from the 80’s are back in the game. The Santa Cruz Slime Balls ride a bit softer and are ideal for rough spots but also in the skate park. 53mm Diameter & 56mm 99a Durometer Contact surface: 17mm Set of 4