Under what conditions must a passenger car tyre be replaced to keep the vehicle roadworthy for Angolan traffic inspections?

1. When the tread is worn down level with the built-in wear indicator bars, or when the tyre shows sidewall bulges, cuts, or exposed cord plies
2. Only when the tyre is completely flat and holds no air at all
3. Only when the tyre is more than 20 years old, regardless of visible condition
4. Tyres never need replacement as long as the vehicle passes an emissions check