Ewan has been editor of Retreading Business since 2006 and of Tyre & Rubber Recycling since the magazine was founded. During this period he has become an expert on the global tyre recycling sector. He has many years' experience as an automotive journalist including a period at Tyres & Accessories.
Hankook AH51 and DH51 Show Tech at its Best
Product advancements in Hankook’s AH51 and DH51 tyres produce outstanding results with strong market leading performance.
AH51 and DH51 Lead Hankook Charge
Hankook’s AH51 and DH51 truck tyres are excelling across the board when compared to their predecessors. It is thanks to advancements in computer processing power, AI, materials science, and 3D printed mould technology that Hankook have been able to deliver a truck tyre with a stepped change in performance from the first to the last millimetre of tread wear. Hankook’s investment in these combined technologies have delivered a cooler running tread, a more rigid tread block and regenerating tread features (appears as the tread wears), resulting in significant fuel savings, damage resistance, wet grip, and mileage benefit for premium fleet partners.
There is a considerable increase in mileage performance for both new tyre patterns, 15% for the steering axle and 20% for the driving axle, as well as a 10 percent reduction in rolling resistance contributing to better fuel economies. The wet performance is 15% to 17% better than the 31 series product, which in testing in the part worn condition gave a 6.3m shorter stopping distance than the worse placed premium competitors latest technology tyre. This significant improvement is due to the 3D mould printing giving a regenerative tread pattern in the 51 series products.
In addition to this, these premium tyres have an extended life through Hankook’s SmartLife Solution, as the AH51 and DH51 are designed specifically to be regrooved and retreaded allowing for a second, third and even fourth life extension to deliver up to 250% additional tyre life. These advanced features are significantly impacting on the CPK performance (cost per kilometre), setting a new benchmark for the industry. Throughout 2022 the AH51 and DH51 have been tested across Europe and the results are impressive. Due to this success the 31 Series is being phased out so existing and new fleet partners can source and benefit from Hankook’s latest generation of premium truck tyres.
“As a company, we place a high value on the sustainability of our products, and therefore our newly developed smart treads fulfil our aspirations for ensuring sustainable and future-proof tyres, and of course also in conjunction with significantly increased customer benefits,” says Jon Cottrell, Hankook UK‘s TBR Manager. He continues „“Intensive testing has shown that, compared to competitors in the premium category, both new SmartFlex products achieve significantly higher performance standards in the lifetime performance chapter, even when the tyre are 2/3 worn, for example in terms of braking distance on wet roads as well as grip and safety in a wide range of road conditions.”
Technical Information
Hankook’s successful SmartFlex line is particularly suitable for regional and local traffic distributions, with the 3PMSF (Three Peak Mountain Snowflake) certification making them a good all year round choice. The newest treads to this range, the SmartFlex AH51 for the steering axle and the SmartFlex DH51 for the driving axle, benefit from Hankook’s advancements in sustainability and tread technologies bringing further improvements to tyre performance.
The base compound of both patterns of AH51 and DH51 was consistently designed for efficiency. The increase in the proportion of low-damping materials contributes significantly to the reduction of principle viscoelastic power loss throughout the tread, therefore less energy is lost, and fuel efficiency is improved. The sidewall compounds were also freshly developed for the new SmartFlex generation. Hankook developers have placed a considerable emphasis on significantly increased resistance to crack formation and material fatigue. Thus, the overall resistance of the SmartLife carcasses used on AH51 and DH51 has been further enhanced compared to the predecessor treads. The new DH51 tyre also has a distinct feature in its notch-tough tread compounds, where special high-performance resins improve the resistance and durability by increasing the molecular weight of the polymers used, thus contributing to an overall higher mileage performance.
The innovative Hankook mixing process IMS (Innovative Mixing System) ensures an even distribution of carbon black particles and rubber molecules within the compounds. In combination with the extension of the mixing times at lowered temperatures, a significant increase in the bonding rate between the carbon black and rubber molecules can thus be achieved. As a result, SmartFlex tyres generate less heat during operation.
The SCCT (Stiffness Control Contour Theory) design technology used in SmartFlex products ensures that the internal pressure distribution is as evenly balanced as possible depending on the application. This results in more stability and less movement in the tyre casing during use, which leads to high durability of the SmartLife carcasses and very good retreadability. For both the belt plies and the carcass itself, the AH51 and DH51 each use special high-strength steel cord materials. Together with the SCCT contour, this results in a consistent contact patch for even wear, as well as improved traction and braking performance.
3D sipes with self-regenerating tread features incorporated into the AH51 and DH51 treads emerge after a degree of wear of between 40 and 70 percent in the tread pattern. The task of these “regenerating” grooves is to lock the tread blocks together in the rolling movement and thus ensure higher overall tread stability and thus resulting in extended mileage over the entire service life. They also make the tyre more robust and less susceptible to external influences, such as poor road surfaces. So-called “hidden grooves” appear from a wear level of around 70 percent and ensure continued high traction and wet grip even in wet conditions until the tread is completely worn out.
The wide tread blocks of the SmartFlex AH51, which can also be used as an all-position tyre, are equipped with additional supports (T.W.E.S. - Tread Wear Equalised Stepper) in the outer grooves and significantly increase the tread stiffness in conjunction with its broad tyre shoulder ribs. They ensure particularly even wear across the entire width of the tyre. This results in further improvements in mileage and rolling resistance. The SmartFlex DH51 has a wider contact patch than its predecessor, which increases traction while improving mileage and rolling resistance. Special sipes on the shoulder blocks, which naturally are under stress on drive axle tyres, help to reduce cracking even during peak loads. In addition, they support tread drainage to further increase traction performance.