SRI claims new runflat offers same comfort as standard tyres

ERJ staff report (DS)

Kobe, Japan -- Sumitomo Rubber Industries, Ltd. said its fourth generation runflat tyres provide ride comfort equivalent to or better than standard tyres, while maintaining runflat performance.

The company said it has adopted four proprietary technologies under the banner, "thermal control technology". These include 'CTT Profile', 'Aramid Casing', 'High Thermal Conductivity Materials' and 'Dimple Sidewall'. Together, said SRI, these have increased the driving distance of cars on flat tyres by 2.3 times, compared with the 3rd generation runflat tyre. With those technologies, Sumitomo Rubber was able to decrease the thickness of the sidewall reinforcement layer by 30% and in turn reduce tyre's overall weight by 3% and vertical stiffness by 6%, which provides ride comfort same as or better than standard tyres.

CTT (Combined Technology Tire) is a new tyre profile using the involute function. It replaces the older DSST profile. SRI said it demonstrates excellent runflat performance with sidewall reinforcement layer and other general performances such as ride comfort with the round tread profile. It also helps reduce tyre weight.

The casing reinforcement uses aramid fibres. The company did not say of these are hybrid yarns or pure aramid, but noted that the stiffness when driving is five times greater than rayon. Aamid is stiffer than conventional rayon. Stiffer aramid casing reduces deformation and heat generation of the sidewall reinforcement layer when the tyre runs flat.

By increasing the heat conductivity ratio of the compounds used for the sidewall reinforcement layer and the sidewall rubber, Sumitomo Rubber said it improves heat dispersion away from the most critical areas. The heat conductivity ratio is improved by 2.5 times for the sidewall reinforcement layer and by 1.5 times for the sidewall, compared with the 3rd generation runflat tyres.

SRI said the high conductivity is achieved by using carbon fibres of high heat conductivity. These are aligned with the fibres running from innerliner to outer sidewall

Finally, the company claims large dimples on the sidewall improve airflow around the tyre to achieve maximum cooling effect.

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Press release from SRI