The purpose of a spare tyre is to provide a replacement if one of the tyres on your vehicle is flat or damaged. This means that it is vital to check your spare tyre as carefully as those in day to day use.
It's also important to be prepared for changing a tyre, which you may need to do in fairly difficult locations (such as at the side of a motorway in the rain). You should also familiarise yourself with the location of the car jack and the spare tyre before you need to use them in a real situation. Ensure also that you have a wheel brace as well as a good, inflated spare tyre.
Spare tyres can be full-size or temporary space saver Mini spares
Mini spares are designed to take up less room in your vehicle and to get you home, but not to be driven on for long periods. Many of the space savers can not be used at speeds over 50mph; consult your space saver wheel or vehicle handbook for specific details.