Corporate News

=Dunlop's 4th Generation Runflat Tires=
"Thermal Control Technology" Enhances Ride Comfort to Be Same as or Better than Standard Tires

2009.10.09

Sumitomo Rubber Industries, Ltd. in Kobe, Japan recently announced that with its new Thermal Control Technology, the company has succeeded in development of the 4th generation runflat tires to provide excellent ride comfort equivalent to or better than standard tires, while maintaining runflat performance of the tire. The 2nd biggest tire manufacturer in Japan has been working hard on development of technologies for runflat tires to contribute to the world in terms of both driving safety and environment protection.

Dunlop developed and commercialized the DENOVO runflat system for the first time in the world in 1970. For the system, a cartridge which contains sealing liquid and is attached on the well of the wheel injects the jelly-like liquid to repair the puncture when the tire goes flat and touches the cartridge. It evolved into DENOVO 2 equipped with the sealant and the anti-bead dislodgement mechanism called DENLOC in 1972 and then to TD Tire with advanced anti-bead dislodgement system in 1979.

In 1995, Sumitomo Rubber developed and commercialized a sidewall-reinforced type runflat tire. This 1st generation runflat tire named DSST (Dunlop Self-Supporting Technology) can be mounted on standard wheels and is compatible with a standard tire.

4th Generation Runlflat Tire

Sumitomo Rubber developed "CTT Runflat Tire" as the 2nd generation runflat tire in 2000. Its unique tire profile design named CTT Profile reduces the tire weight by 10% and the vertical stiffness, index for ride comfort, by 15%, compared with the 1st generation runflat tire.

The 3rd generation runflat tire was developed in 2003. The aim was further reduction of overall weight and vertical stiffness. The company succeeded in reducing the weight by 3.5% and the vertical stiffness by 7% by reducing the heat generation of and using stiffer compound for the sidewall reinforcement layer as well as lowering the heat generated on the bead apex, compared with the predecessor.

And today, Sumitomo Rubber thoroughly examined means to reduce the heat generation by its proprietary "thermal control technology" and gave a birth to the 4th generation runflat tire. When it runs flat, a tire repeats significant deformation and the sidewall reinforcement layer generates heat at every rotation of a wheel. The company adopted 4 proprietary technologies namely CTT Profile, Aramid Casing, High Thermal Conductivity Materials and Dimple Sidewall for the tire and increased the driving distance of cars on flat tires by 2.3 times, compared with the 3rd generation runflat tire. With those technologies, Sumitomo Rubber was able to decrease the thickness of the sidewall reinforcement layer by 30% and in turn reduce tire's overall weight by 3% and vertical stiffness by 6%, which provides ride comfort same as or better than standard tires.

History of Development of Runflat Tire Technologies

Thermal Control Technology

Features

  1. CTT Profile

    CTT (Combined Technology Tire) is Sumitomo Rubber's proprietary technology. New tire profile using the involute function 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 tire weight.

    New Tire Profile Using Involute Function

  2. Aramid Casing

    Aamid is stiffer than conventional rayon. Stiffer aramid casing reduces deformation and heat generation of the sidewall reinforcement layer when the tire runs flat.

  3. High Thermal Conductivity Materials

    By increasing the heat conductivity ratio of the compounds used for the sidewall reinforcement layer and the sidewall rubber, Sumitomo Rubber successfully disperses the heat which concentrates to the damageable area of the sidewall reinforcement layer. 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 tires.

  4. Dimple Sidewall

    The dimples carved on surface of the sidewall provide better heat radiation through turbulent airflow, which shows the effect of reduction of approximately 10?, compared with tires without dimples.

    Enlarged pictures of dimples

    Runflat tires are more and more fitted on new cars on perspectives of safety as well as resource saving and fuel efficiency brought by elimination of spare tires. Sumitomo Rubber has a strong belief in that development of safe and eco-friendly tires is the social responsibility of tire manufacturers. Sumitomo Rubber is committed to promote the development of high performance tires which are safe, eco-friendly and useful to the world people with its proprietary technologies.