I've got one pair of soft and one pair of medium on mine and I can't really tell much of a difference between them. Although mine are very old and the rubber is getting pretty hard. You might want to see how long the soft tires last before you get your next set. If its a lot of loose terrain like gravel, sand, and mud then harder tires are fine. On grass, firm rocks, and pavement the softer tires will give you a lot better traction and control. Good luck! B)