Car tires should be checked for age and tread depth to ensure safety. The DOT code on the sidewall reveals the manufacturing date. Tread depth, with a legal minimum of 1.6 mm in India, is crucial for grip, especially in wet conditions. Tires should ideally be replaced when tread depth reaches 3 mm, as performance degrades significantly below this point. Tread wear indicators (TWI) on tires signal when replacement is immediately necessary.