Tyres: Black Rubber Magic

Tyres: Black Rubber Magic

Think a tyre’s just a black rubber hoop? Might be time to check your knowledge of the gear you rely on to safely reach your destination, even during a storm or blizzard.

2. 4. 2019 Škoda World Innovation & technology Technology

The experts at ŠKODA’s chassis development department specialise in the development and testing of new tyres. Tyres are always individually designed for a specific vehicle in collaboration with independent manufacturers. Meet our tyre experts Dušan Petrovický, Ladislav Havlíček and Jan Ševčík.

“If you can’t brake it, you can’t fake it,” says Ladislav Havlíček, who is in charge of new-tyre development at the ŠKODA chassis department in Mladá Bolesav. In his opinion, this is more than a popular Czech saying: it is a valid rule that applies to one of the many attributes required of a tyre. These black rubber hoops are much more important than many drivers realise.

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Ladislav Havlíček
chassis development department at ŠKODA

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Fifty shades of black

Tyres provide a point of contact between the car and the road, determining whether you reach your destination safely and in time or end up in a ditch. Over the past twenty years, tyres have been extensively developed. Experts from Mladá Boleslav have played a role here, with the team developing new tyres in cooperation with individual suppliers.

The experts at ŠKODA do not see a tyre as one seamless object, but as an intricate piece of equipment with a complex internal structure. “People think it’s just about pouring a mixture into a pan and turning on the oven, but this is not the case. You can burn the simplest cake if you don’t follow the recipe,” says Ladislav Havlíček. And while you only need one mix to bake a cake, a tyre is composed of up to twelve components. Aside from rubber, it needs to be strengthened with textile and steel wires, and steel cords are also used.

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Collaboration with suppliers

Tyres for ŠKODAs are imported from several countries, but the experts in Mladá Boleslav always have the last word. Every type of tyre is subject to extensive testing and assessment. In the Czech Republic, tests are carried out on ordinary roads, VW test tracks, and at reputable companies, such as Continental, Goodyear, Michelin and Bridgestone. Tyres destined for use on race cars are trialled at the famous Nürburgring race track.

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Every type of tyre is subject to extensive testing and assessment. Resistance to aquaplaning, that is the tyre’s ability to extrude water from under the wheel, is also evaluated, as is overall handling on wet surfaces.

Approximately twelve parameters are assessed in dry conditions alone. These include stability, lateral traction, acoustic comfort, and wet grip – no, these are not punk bands, but some of the most important attributes of a tyre. Resistance to aquaplaning, that is the tyre’s ability to extrude water from under the wheel, is also evaluated, as is overall handling on wet surfaces. The tests are aimed at ascertaining how comfortable driving with a certain tyre is, as well as to determine when it reaches its limits. This is crucial for knowing whether the tyre will help you to stabilise the car, or whether it will make matters worse by causing your vehicle to slide. Naturally, criteria that interest all customers, such as noise levels and service life, are also taken into consideration. ŠKODA tests tyres not only for Europe, but also for China and India, where it is expected that poorer road conditions will give tyres a harder time.

ŠKODA is thought to be very particular by tyre manufacturers. It is not unusual for there to be up to eight rounds of feedback before the developers finally approve a tyre for production. Consequently, every ŠKODA OCTAVIA, FABIA, SUPERB, KODIAQ, KAROQ and SCALA is supplied to dealers with tyres specifically designed for that particular vehicle. “The customer always purchases our car with dedicated tyres that are perfectly matched to the car’s specifications,” says ŠKODA’s Dušan Petrovický.

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The tests are aimed at ascertaining how comfortable driving with a certain tyre is, as well as to determine when it reaches its limits. Naturally, criteria that interest all customers, such as noise levels and service life, are also taken into consideration.

Making magic with fragile webs

In Mladá Boleslav, they say that tyres are like black magic. People expect a lot from a tyre: it shouldn’t be noisy, it should have optimal rolling resistance, run smoothly in dry weather, brake effectively on wet surfaces, perform well in different temperatures, have good traction in order to effectively transfer the engine’s power to the road, and minimise sliding. Very often, however, these requirements are mutually exclusive.

“We can visualise this set of requirements as a web, with all the individual properties of the tyre at each end. The moment you pull one end, you inevitably affect the other properties as well. For example, if you improve rolling resistance you diminish the braking distance or traction on wet surfaces,” says ŠKODA’s Jan Ševčík. Companies try hard to develop new materials with generally better features, but the process is complicated and requires use of advanced, almost space-worthy, technologies.

When it comes to choosing tyres, you need to keep an eye on several key important parameters to ensure that they will be a good fit for your car. This is why there is an information label on each tyre, setting out all of the important information.

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But what do those numbers and letters mean?

205 - tyre width in millimetres [mm], measured from sidewall to sidewall (in this case, 205 mm)
50 - the aspect ratio of the tyre. This is the height-to-width ratio of the tyre, expressed as a percentage [%] (in this case, 50% of 205 mm, i.e. 102.5 mm)
R - denotes the construction of the tyre. In this case, it is a RADIAL tyre – this term refers to how the individual plies of the tyres are structured (the ply fabric is cord). These cords always run perpendicular to the tyre’s direction of travel
17 - the rim diameter ["]
XL - denotes a reinforced tyre design (XL stands for Extra Load)
93 - the tyre load index, expressing the maximum permissible tyre load in kilograms [kg] (in this case, 650 kg)
H - the tyre speed rating, expressing the maximum vehicle speed [km/h] for which the tyre has been made (in this case, 210 km/h)
FR - indicates that the rim is protected from damage if scraped against the kerb

Nature matters

In recent years, rolling resistance has become a closely observed parameter. The higher the tyre’s resistance, the more effort is required by the engine, which pushes up fuel consumption. The values may seem insignificant – in the per mille range, but cutting down by just one unit per mille means a reduction in CO2 by 3 grams per 100 kilometres. This is very significant when we consider overall capacity and mileage. Rolling resistance is one of three key parameters that EU regulations require manufacturers to specify on tyre labels (which are much like the tags you will find on electrical appliances). In addition, these labels specify the tyre’s wet grip and acoustic value, or how much noise it makes.

3 key parameters

Rolling resistance is not the only parameter relevant to environmental conservation. As the tyres lose material over time, they become an environmental burden. “We are now attempting to minimise the tyres’ environmental impact and extend their lifespan,” Dušan Petrovický explains.

Even though modern tyres look almost identical to the ones from fifteen or twenty years ago, in many ways they have improved; they are safer, more economical, easier on the environment, and have a longer lifespan. Effectively, due to the application of modern technologies, tyres have reached their peak and future steps will constitute but a small improvement requiring great effort. Nevertheless, the experts in Mladá Boleslav work hard to ensure that ŠKODA cars are fitted with the best tyres currently available.

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