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08/01/2019
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Historic tires

 

It's round, black and, only apparently, disarmingly simple. Yet tires are rather complex objects and some are even considered iconic. Not surprisingly, then, Pirelli recently dusted off the glorious name Stella Bianca, which had been successfully used for over twenty years on and off race tracks, one of Pirelli's long-lasting icons and the first “modern” tire in the history of the company.

Paolo Ferrini

It's round, black and, only apparently, disarmingly simple. Yet tires are rather complex objects and some are even considered iconic. Not surprisingly, then, Pirelli recently dusted off the glorious name Stella Bianca, which had been successfully used for over twenty years on and off race tracks, one of Pirelli's long-lasting icons and the first “modern” tire in the history of the company.

The choice of this "historical name" was far from accidental since, as Pirelli staff underscores, it is a product destined for classic cars dating back to as far as the 20s all the way to the 60s. For this reason, the 21st century Stella Bianca, while reproducing the look of the original tire, is rife with modern technologies and a compound able to guarantee maximum performance in terms of efficiency, safety even on wet roads and environmental sustainability. The structure, on the other hand, looks back to the past. After more than half a century, Pirelli has gone back to producing non-radial tires. The “new” Stella Bianca, in fact, is a cross-ply tire: a technical choice made to guarantee an original look and feel.

 

Vintage racing tires

Until the end of the 1950s, it was common practice for racing tires to be basically universal and were used on Formula 1 single-seaters, sports cars as well as the fastest GTs of the time. The most common were the Dunlop R7s with diagonal cross-plies and serpentine treads, produced with normal and wide section profiles. Structure and design were the same for everyone. The only differences concerned the varying degree of softness (green, red and white stickers).

Early August 1961, Stirling Moss wins the German Grand Prix on the Nürburgring circuit with a RobWalker Team Lotus 18/21 equipped with Dunlop’s revolutionary wet D12 (dry D9). The decision to use them was nothing short of a gamble, since these tires were designed for wet conditions and that day the German circuit was almost entirely dry. In the end, however, that was the winning choice because, thanks to their softer compound, the Dunlop D12s had higher hysteresis and superior grip. The choice, as said, overturned the technical values at stake, favouring the success of a single-seater with a smaller engine against the powerful Ferrari 156 which had been dominant until then. Thus the idea of a dedicated racing tire, albeit with a sculpted tread, was born.

 

X equals radial

If, as said, the new Stella Bianca marks a “wilful” waiver of radial technology to better reflect the behaviour of classic cars, the Michelin X instead deserves the credit for having industrialized radial technology in the second post-war period, going down in history as the radial par excellence. At that time, "standard radials" were nothing short of revolutionary, and all manufacturers looked at replicating that technology. However, since the steel wire mesh could not be used in the containment belt, given Michelin’s 20-year-long patent, many resorted to textile solutions. In 1951, Pirelli presented its first Cinturato - another legendary name - as the first example of a fabric-reinforced radial, followed by similar proposals from Continental, Dunlop, Firestone and Uniroyal, all stimulated by the growing interest of most European car manufacturers in this solution. It is no coincidence that at the beginning of the 1970s, as Michelin’s patent expired, 80-90% of all new cars were equipped with radial tires. In the meantime, radials found new applications. In 1952 Michelin unveiled its first truck radial, and in 1977 the first radial made its debut in Formula 1 on Renault, two years later it was the turn of the first agricultural radial and in 1981 the first aircraft radial was fitted on Dassault’s Mirage III fighter aircraft. It's no wonder, then, that the Michelin X has become synonymous with radial tires.

 

Lifeguard and  Denovo; who’s afraid of punctures

At the beginning of the 1970s Dunlop launched Denovo, the first example of a self-sealing tire, the first attempt by the British company to offer a solution against punctures. Goodyear, though, had already been toying with the idea for some 40 tears and in 1934 introduced Lifeguard - another iconic name - as the first example of a long series of tires by the American company that led to creation, in 1992, of Goodyear’s EMT (Extended Mobility Technology), the first example of a self-supporting tire that would soon become the first run-flat available as original equipment on a production car (Corvette).

 

Hakkapeliitta like winter

First presented in 1936 by SuomenGummitehdasOsakeyhtiö (today Nokian), in the wake of the great success of the Kelirengas, a specialist truck tire with a robust tread able to handle the most extreme winter conditions, the name Hakkapeliitta has always been associated to extreme winter tires. This proved to be a truly revolutionary tire for driving on the narrow and snowy roads of Scandinavia, and was soon to create a new market segment: winter tires.

Tire grip has always been a crucial issue and this compels us to take a step back and talk about Pirelli’s Nero Ferrato, another legendary name. Today, tires are (almost always) black. But that was not always the case. Until 1904 they were lighter in colour, as sulphur (necessary for the curing process) was the only chemical added to the rubber. Nero Ferrato was not only the first black Pirelli tire, but, as its name suggested, it included another important innovation.

Until then, in fact, treads were completely smooth tread. To ensure greater grip, tires used to be wrapped in a studded leather belt. In the Nero Ferrato, however, the studs were inserted directly into the tread compound so that the protruding heads offered as much grip, if not more, without having to resort to uncomfortable and complicated leather belts.

 

Energy and other stories

For the first time, in 1992, Michelin turned the spot light on the environmental impact of tires with its first Energy series, which is still remembered as the first to integrate silica into the tread compound. Perhaps the public at the time did not respond as the French manufacturer had expected, but Michelin Energy certainly stimulated the development of products with vegetable-based compounds (corn, citrus juice, dandelion...). And, perhaps, this is the reason why it is considered an icon.

 

VINTAGE TIRES STILL HAVE A MARKET

Pirelli’s new Stella Bianca is a product designed for a rich market niche in which, for a whole lot of reasons, only a few manufacturers are found. This is confirmed by Angelo Di Sabato, owner of Angelicogomme, a reference point for collectors of vintage cars in the Rome area. "Tires are a small niche in what is already a niche, the vintage car repair sector. And yet, for this very reason, competition is almost non-existent. So much so that the distribution network in Italy is basically made up of two companies: Fratelli Rossi Pneumatici in Bologna and Musso Gomme in Turin. Vintage cars, lovingly stored in private garages waiting to be shown off at meetings, need tires that perfectly reflect the same characteristics of those that originally equipped them and are, therefore, able to enhance their performance.

"When it comes to 'vintage objects', owners value their authenticity above all else: however, the perfect vintage tire must still meet the quality standards needed to ensure adequate road handling. They are the final touch that completes a work of art," according to the staff at Angelicogomme. "Vintage tires may be tubeless or have an inner tube. And then there is a choice of the inscriptions that will affect the design of the tire: a modern tire mounted on a vintage car would not look authentic. All these requirements, combined with a limited production, will significantly increase the price of "classic" tires as opposed to modern products”. And then there's the human factor. "Our customers expect to receive technical answers. We don't just have to know about vintage vehicles or tires," Di Sabato continues. "We need to know what kind of tire were found as original equipment on every car, information that even the owners of these cars very often do not have. For the rest, "classic" tires are not really different from other modern tires. "The compounds are the same, while the designs replicate the original ones. They do not require special equipment. Vintage tires, however, must be disassembled and reassembled by hand: a practice that my father has always mastered driven by his passion for classic vehicles. He's been doing this since he was young and we are all still learning from him," concludes Di Sabato.

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