What size socket do you need to remove a spark plug from a 2003 KIA Rio?

To remove a spark plug from a 2003 Kia Rio, you will need a 16mm (or 5/8 inch) spark plug socket. It's important to use a socket with a rubber or magnetic insert to help grip the spark plug. Additionally, a ratchet and extension may be necessary to provide better leverage and access to the plugs.