For a safe trip in a passenger car, it is essential to carry the necessary tools to **change the spare wheel**. This is because:

- **You must always carry a spare wheel** in the vehicle. This wheel should be slightly more inflated than the others to ensure its effectiveness in case a change is needed.
- Checking the condition of the tires is crucial before a trip, and having a spare wheel ensures that you can fix a puncture or damage to a tire during the journey.
- Carrying tools to change the spare wheel is indispensable, as a damaged tire can occur at any time and place, and having the right equipment will allow you to continue your trip without major inconveniences.

Therefore, it is essential to be prepared to change the spare wheel, thus ensuring the continuity and safety of the trip.