What should you check regularly if your car has a spare wheel carried outside the body of the car?

You answered correctly. If your car has a spare wheel carried outside the body, you should regularly check both the double safeguard (to be sure the wheel is securely fastened and won't fall off while driving) and the tyre pressure (so the spare is usable if you need it in an emergency). These checks ensure the spare wheel is safe and ready for use when needed, helping prevent accidents or being stranded with an unusable spare. Rolling resistance does not need to be checked for a spare wheel that is not currently in use. In summary, always check the security and air pressure of an externally mounted spare wheel.