A space saver wheel or spare wheel as it is commonly known as effectively a backup in case you have a blown tyre or its goes flat. The space saver wheel is normally stored in the well area of the boot and is slightly smaller than your other wheels and has a maximum speed limit. It is not designed as a replacement but a temporary measure so you can get the blown one repaired.
More and more car manufacturers have begun to phase out space saver wheels opting for tyre repair or sealant kits instead. Many drivers are not aware of this change and assume the space saver wheel is safely tucked away. Other vehicles actually have missing spare wheels as it has either been used or sold without one.
A replacement space saver wheel can be easily replaced at relatively low cost.