Just a bit of rubber?? Not any more, Tyre manufacturers are continually investing to make their tyres the best. Run flat tyres are becoming more and more popular, so here is a little bit about them. Hold tight……
A run-flat tyre is a pneumatic tyre that is designed to resist the effects of deflation when punctured, and to enable the vehicle to continue to be driven at reduced speeds (upto 55mph) and for limited distances of up to 100 miles depending on the type of tyre.
There are three basic technologies currently available
Self-supporting run-flat tyres are fairly common on light trucks and passenger cars and typically provide for the vehicle to drive for 50 miles at around 50 miles per hour. However, if the tyres are treated to this kind of punishment, they may still be irreparably damaged in the process. In addition, if the tyre is punctured in the sidewall or at the edge of the tread, repair may be impossible or unsafe.
Self-supporting run-flat tyres typically carry a 15% - 27% weight penalty over similar standard tires, or additional 2-3 kg. The additional mass concentrated on the outer edge of the wheels can impose a significant performance penalty due to greater rotational and unsprung mass.
Bridgestone run-flat tires are supplied on most new model BMWs. BMW is promoting these as a safety feature and as an alternative to carrying a spare tire.
These tyres contain an extra lining within the tyre that self-seals in the event of a small hole due to a nail or screw. In this way, the loss of air is prevented from the outset such that the tire is either permanently self-repairing or at least loses air very slowly.
In this system, there is an additional support ring attached to the wheel that can support the weight of the vehicle in the event of a loss of pressure. While these systems generally offer better ride quality because their sidewall's stiffness can be equivalent to a standard tyre, the requirement to have both special wheels and special tyres increases cost and limits these systems from widespread use.
Depending on the design, some run-flat tyres perform better than regular tyres, and some slightly worse. Some run-flat tyres have a 20% higher rolling resistance, in part due to their added structural material and mass. On the other hand, internal bracing in some run-flat tires reduces deformation, with the opposite effects of reducing rolling resistance and improving fuel efficiency.
Further advantages are derived from not needing to carry a spare wheel: The space can be used for other purposes. Also, the absence of a spare wheel contributes to lower vehicle weight which will in turn reduce fuel consumption, reduce harmful exhaust emissions, improve performance, handling and braking characteristics..
Due to reinforcement in tire side walls, run-flat tires usually give firmer rides compared to conventional tires.
Nitrogen has been used for many years to fill aircraft tyres, racing car tyres and construction vehicles…..Why?
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