When to Replace Soft Dirt Tires

• Soft dirt tires are made of harder rubber; the knobs that circumvent the tire are shaped in a more rectangular fashion so they can propel you through the soft soil. These tires will wear down slower than hard dirt tires for several reasons: one, the tire rubber is harder; two, the soil is softer. These should be replaced just as often, however; the soft soil means you need more traction. When the edges wear off the tire studs, these should be replaced for a fresh set. If any knobs break off, then replace right away.
  
  

Hard Soil Tires

• Hard soil tires have short knobs; they are made of softer rubber due to the fact that the treads do not need to provide as much "paddle-action" as softer tires. You would be uncomfortable riding on hard dirt with those knobby soft soil tires. These tires will wear out because of the hard dirt and soft rubber. Replace them when the knobs wear down more than a 1/4 inch or you can see that the knobs are worn unevenly. Again, if any of the knobs break, replace right away.
  
  

Racing

• For racing and competitive riding, the rule of thumb is to replace your tires every day or after each event. If you have several events in one day, it won't hurt to ride a fresh pair of tires for each one. The choice is up to you, but, when in competition, it helps to have every possible edge. Changing tires will only increase your chances of outperforming the other riders.