Japanese tyre maker Bridgestone reckons it has solved some of the drawbacks associated with run-flat tyres with a new generation of rubber that, it claims, increases ride comfort and cuts road noise.
The poor ride associated with run-flats is caused by the tyres’ very stiff sidewalls, which help keep the tyres rigid in the event of air loss. However, this new breed of run-flats includes three new technologies that allow a softer tyre sidewall to improve pliancy over bumps.
The chief advance is a new material called NanoPro-Tech, which reduces the friction and heat build-up that threatens to break up a deflated tyre.
The other two technologies are applied depending on the type of vehicle.
Bridgestone says the carcass ply, which runs across the tyre rather than around it, will be suitable for high-end vehicles requiring an exceptional ride. It contracts as the deflated tyre heats up, stiffening the sidewall only when needed to stop the tyre rolling off the rim. This allows a more flexible sidewall when the tyre is inflated.
The third innovation — more suitable for SUVs and vehicles whose tyres have tall sidewalls — consists of a series of ribs that dissipate heat.
The first cars with these run-flats will go on sale this autumn. The tyres will eventually be offered as aftermarket replacements so that owners of cars with current run-flats can benefit.