A timing belt is normally replaced every 50,000 to 100,000 miles, but replacement intervals vary between car manufacturers. Check the owner's manual or an online maintenance schedule for replacement interval rates for a specific vehicle.
After tens of thousands of miles, normal wear and tear takes a toll on the synthetic rubber material from which a timing belt is made. When the grooves begin to wear, the likelihood of a sudden snap heightens. The timing belt on a vehicle provides the rotation for the engine's camshaft and crankshaft so that the pistons and valves continue to move in sync. Without the rotation, the engine is not able to run, which makes a functioning timing belt a crucial component to a healthy vehicle.