At what tread depth should tires generally be replaced?

The correct tread depth for replacing tires is typically around 2.5 cm, which is approximately 1 inch. This depth is significant because adequate tread depth is essential for maintaining traction, especially in wet conditions. Treads help channel water away from the tire, reducing the likelihood of hydroplaning and providing better grip on the road.

When tires wear down to a tread depth of about 2.5 cm, they no longer provide optimal safety or performance, leading to decreased handling capabilities and longer stopping distances. Therefore, monitoring tire tread depth is crucial for safe driving. A tread depth of 2.5 cm serves as a guideline in many jurisdictions, including recommendations from safety organizations.

In contrast, the other options provided exceed the typical replacement guideline, as they suggest depths that are much greater than necessary. Regular maintenance and checks on tire condition can help ensure you're operating with safe and effective equipment.