A spare tyre is actually an additional tyre present in your car. It is used when one of your tyres undergo any kind of physical damage in the middle of your drive or if there is any kind of emergency to change a tyre. In this case, the spare tyre comes into play and it replaces the damaged tyre. This way you can escape unwanted trouble that could happen in this case. By replacing your old tyre with a spare tyre, you get a chance to drive your car to the nearest service centre without any hassle. However, the spare wheel given with your car is not a permanent replacement option for the original tyres as it should be driven to a limited number of miles suggested by the manufacture. Hence, you should not go and run it any loger than that.
Since using the spare wheel provided along with the vehicle is not quite a frequent deal for most of the people, nowadays most of the car manufacturers have repalced the full-sized spare tyres with narrow and compact ones. These are called space-savers or donut tyres. They have a smaller profile than the usual spare tyres and hence, are lighter in weight and save a lot of space. However, the space savers are not meant for long distance travels, but are only suitable for short distance drives. They have even less durability than the regular spare tyres and come with a maximum speed of 80 km/h and is allowed to run only 250 km.
Advantages of Space-Saver Tyres:
There are several advantages of a space-saver tyre over a regular spare tyre:
1) As the name suggests, the primary purpose of a space-saver tyre is to save space in the boot of your car.
2) Also, it makes the car lighter in weight that reduces exhaust emmision and leads to more fuel effiviency.
3) It is human nature that if we replace a regular tyre with a full-sized spare tyre, we keep on running it as a permanent one untill its life is over. In this case, you just keep the damaged tyre in the boot of your car and forget about it. But, in case another of your original tyres gets screwed up, then you are completely stranded. So, to avoid this kind of unwanted situations, these tyres come with a totally different profile and thus, they cannot be driven to a large distance.
4) The space saver tyres are coloured in bright shades like orange, yellow and red. This way it reminds the driver that it is a spare tyre that is fitted in the car and it needs to be replaced with a regular tyre as soon as possible.
Disadvantages of a Space-Saver Tyre:
Although a spare tyre is a lifesaver when the tyres which are in use go pop, it cannot be kept in service for a long period of time. So, if it keeps running for a longer distance than that recommended by the manufacture, it may lead to loads of troubles for both you and your vehicle such as:
1) A space-saver tyre is not as durable as the regular spare tyres.
2) The polyester below the space-savers do not have enough plies as regular tyres and hence, they lack the strenght that is essential for a regular tyre to run.
3) As it lacks the required plieslayers, a space-saver is highly limited to puncture resistence and cornering ability.
4) A space-saver tyre is narrower than a regular spare tyre and have a smaller contact patch that reduces the amount of traction for the tyre.
5) These tyres have increased stopping distances and provide your car a bad handling quality.
6) If you use a space-saver tyre for a longer time, it could lead you to dangerous situations as in these tyres ABS and traction control is not very effective.
7) Long-term use of spares can also cause serious mechanical problems to your vehicle.
8) Also, the space savers are smaller in diameter than the regular tyres that can put a lot of stress on your differential.