The Incredibly Strange Pirelli BS3 Tire Featured Removable Tread You Could Change Yourself

Pirelli Bs3 Topshot

Normally, tread separating from a tire is a sign that something’s gone catastrophically wrong. Be it due to manufacturing defect, dry rot, or simply heavy wear, tread separation is typically marked by incessant thwapping followed by destroyed quarter panels. But what if tread separation was a feature rather than a defect? Meet the Pirelli BS3, a tire from which the tread was meant to separate for the sake of year-round driving.

Wait a second, what about the BS1 and BS2? Well, they didn’t really exist. The letters in the BS3 alphanumeric stand for battistrada separata, or separate tread, and the 3 stood for the three tread bands. Here’s how the BS3 worked: Tread bands were available in both summer and winter tread patterns and could be slipped on simply by deflating the tire casing. Once the pressure was pumped back up, grooves and air pressure would work to hold the bands to the tire carcass. No adhesives, no bonding through vulcanization, no problem, right?

Pirelli Bs3 7
Photo credit: Pirelli

According to Fondazione Pirelli, this absolutely insane tire was the brainchild of two men: Giuseppe Lugli and Carlo Barassi. See, back when Lugli was in charge of the Pirelli Rubber Sector’s Physics Laboratory, he imagined a tire with separate tread and casing, an idea that never really got off the ground at first. Barassi then refined this concept, starting with a special tire carcass and separating the tread into three bands kept apart by precipitation-evacuating channels. The channels also served two extra purposes; to keep the tread bands in place and allow fitment of tungsten spikes for winter use. Barassi then pinched a summer tread pattern from the Pirelli Cinturato 367, whipped up a winter tread pattern, and unleashed the BS3 at the 1959 Turin Motor Show.

Pirelli Bs3 8
Photo credit: Pirelli

To showcase the effectiveness of the BS3 in slick conditions, Pirelli slapped a set of BS3s on an Alfa Romeo Giulietta and had skaters in really short dresses chase the car around an ice rink. I’m not sure if the skaters’ outfits were necessary for this publicity stunt, but it was Italy in the 1950s so I’ll just roll with it. While this was certainly a neat ad, the real marketing genius came by partnering with the Autogrill network of roadside restaurants and service stations to sell and install BS3 tread bands along the Autostrada del Sole running from Milan to Naples. Presumably, the idea was that owners of BS3 tires could get winter or summer treads swapped on while they had a light snack. Of course, the promotional displays for the BS3 would also alert other motorists of the tires’ presence. Not a bad plan if you ask me.

Pirelli was immensely proud of its BS3 tire, so in addition to print ads, the Italian company took out some airtime to promote this tire innovation. Check out the BS3 spot some two minutes and 33 seconds into the above compilation of ads. While the ad likely provided decent exposure for the tire, I’m not sure what I learned from this advertisement other than to not use a giant flower as an umbrella during wintertime. In fact, it’s worth watching the entire video because it’s absolutely surreal. In addition to the strange visuals, the backing tracks consist almost entirely of slapstick sound effects, creating the ambiance of comedy collapsing in on itself.

[Editor’s Note: Agreed; you should watch that. It’s out there. -DT]

Pirelli Bs3 2
Photo credit: Pirelli

So, did the Pirelli BS3 actually work? Well, yes and no. Motorsport Magazine had a less than stellar experience with BS3 tires during an outing at the Nurburgring. While testing an Auto Union 1000, a band detached from a rear tire, creating a little bit of a situation. The spontaneous mobile tread band evacuation likely caused a great deal of fuss in the Pirelli press office, as a comparison test between the BS3s and Pirelli Extraflex tires was quickly arranged. Not just some parking lot cone work, this comparison test consisted of a tour of Britain and circuit lapping at Oulton park. Bold stuff. While some rubber came detached, the tread bands stayed put, and Motorsport Magazine had some very kind words for the BS3 tires.

[…] but it is significant that each improved his lap times by approx. 5 sec. when using the BS3-shod Oxford. These tyres at first give a feeling of instability, due to their flexible casings, but their superior grip soon becomes evident and corners begin to be taken in impressive drifts. It was particularly noteworthy that whereas the Extraflex screamed loudly as tyres do when tortured in this fashion, the BS3s were uncannily quiet. This silent running is a valuable asset to those who like to hurry round corners and roundabouts without attracting unwelcome attention.

Driving like a nutcase without raising suspicions sounds quite nice, although it sounds like BS3 tires had some very strange handling characteristics. In addition, Pirelli notes that 23 of the 26 BS3-equipped participants in the 1961 Monte Carlo rally finished — a fairly strong showing for the tire. Still, the remote possibility of tread detachment was one that lingered, and the tire’s patented nature meant that imitators didn’t really exist, preventing a wider audience from discovering the joyful weirdness of swappable treads.

Pirelli Bs3 4
Photo credit: Seller/Autobelle

In the end, the BS3 was rather short-lived, with production ending in 1964. However, the BS3 spawned a tire much closer to Giuseppe Lugli’s original concept, this time simply called the BS. It may have featured a name that didn’t translate well to English, but it soldiered on until advances in cars and tires consigned detachable treads to the dustbin of history. While we haven’t seen anything like the Pirelli BS3 in decades, it holds a very important place in tire history. Per Pirelli, lessons learned from the BS3 and the subsequent BS were put into practice with Pirelli’s first dedicated winter tire, the MS35.

Not only did Sandro Munari win the 1972 Monte Carlo Rally with a Lancia Fulvia shod with Pirelli MS35 winter tires, Pirelli kept developing winter tires, pushing them to places they’d never been before. Today, Pirelli makes Ice Zero winter tires for icy conditions, Scorpion winter tires for SUVs, and Sottozero winter tires for really fast stuff like the Lamborghini Huracan and the Porsche 911. It’s strange to think that in a way, the very peculiar Pirelli BS3 is partially responsible for being able to truly enjoy Lamborghinis in the snow. That’s not a bad legacy if you ask me.

Lead photo credit: Pirelli

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19 Responses

  1. this seems wacky now… but just remember that tires at this time still were not belted and already had awful handling characteristics. But then again, cars barely had 100hp in the US and even lower in Europe. Drive an MG TD and tell me that these tires would really make it that much worse.
    I could totally see these working fine for daily use back then.

  2. ‘some very strange handling characteristics’. Huh. So, squirmy, but good grip while quiet. That sounds … right terrifying: turn in, tire leans under load, then bites, but doesn’t warn you when it’s about to let go. Yikes!
    But, it’s a cool history-dive: I have never heard of this idea. Thanks!

  3. Yeah even today retread tires under load separate with modern bonding materials. Old style tires attached by tire pressure alone probably created slipping and heat between the base and tread areas but also no mention on how often you need to check tire pressure and inflate due to loss of psi. Also how flexible were the treads in case of air overfill? How would they work as hydrogen filled tires?
    File under great idea under perfect conditions unworkable under real life situations. Kind of like Joe Bidens plan for everything. JK.

  4. Re: the ad compilation, for the love of Jesus Fitzgerald Christ, esq. please, don’t watch that before sleep. That thing will haunt your dreams.

    Nereo Negidi, whoever you are, you belong to the Twilight Dimension!

    1. I love European avant-garde advertising of the 1950s and 60s. You can find so much full-send, free reign experimentalism in the capitalist marketplace. It’s like their marketing was done simply by feel, conceived over absinthe and filterless cigarettes, in a dark smoky corner of an artsy basement jazz bar somewhere in an alley near the red light district.

      Definitely watch this video! Knowing that things like this were part of the culture, presented regularly to the public ordinarily, seriously, and without flamboyance, modesty or further exposition, helps to explain a bit of the differences between European and North American cultures.

  5. The entire concept seems so ’50s-’60s, in the best possible way. As in, technology making crazy new things possible but combined with a broad base of users who could still be largely counted on to take such things seriously.

    Can you imagine how many cars would be running around completely without treads if this were available now?

    “Dude, it’s like slicks!”…or more likely “huh, yeah, I forgot but it’s not a big deal, right?”

  6. I feel like tooth channels for the bands would’ve gone a long way towards making these more viable. Friction fit seems like a terrible idea. It would’ve added a bit more to the manufacturing cost of the base tire, but would’ve prevented band slipping and would’ve allowed them to stay in place if the tire was underinflated. Like those LEGO tank treads (part number x1681 for those interested).

    1. Yeah, I don’t want to say the entire idea was bad; after all, tires currently hold onto wheels through just friction fit (beadlocks withstanding). I could see this working for smaller power vehicles, and being improved to higher powered vehicles. But then you also get diminishing returns; why not just replace the whole tire and have a more robust solution? Oh hey, we already do that!

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