Natural rubber comes from latex, milky, pale, and off-white. Early car tires in the 1900s were white or light-colored and wore out far faster than modern ones. When manufacturers discovered that mixing carbon black, a fine dark powder from burning hydrocarbons, into rubber dramatically improved its strength and resistance to wear, heat, and sunlight, it became a permanent part of tire compounds. The black color is the visible signature of that chemistry. Binney and Smith, the company behind Crayola crayons, was one of the earliest major suppliers of carbon black to the tire industry.
Daniel notices that almost every tire he sees is black and wants to know why. The episode covers the color of natural rubber, how carbon black transformed tire durability, the Crayola connection, the complicated history of the whitewall tire, and a 2026 study from the University of South Florida that finally explained the molecular mechanism behind carbon black’s reinforcing effect after more than a century of use. The closing line reframes the color of every ordinary tire.
Daniel is nine. He asks the questions, refuses to accept easy answers, and picks every episode topic himself.
MomCo-host & Researcher
Mom does the digging - finding the sources, checking the claims, and translating them into something a nine-year-old will actually sit still for.
Things to remember
01
Natural rubber is off-white. Tires are black because carbon black is added to improve performance.
02
Carbon black dramatically improves tire strength and resistance to wear, heat, and sunlight degradation.
03
Binney and Smith, the company behind Crayola crayons, was an early major supplier of carbon black for tires.
04
Scientists only produced a clear molecular explanation for carbon black's reinforcing effect in 2026.
“The black color of an ordinary tire is a chemical signature, not just a style choice.”
Mom
Full transcript9 min · 996 words
DanielMom, I just realized something. Almost every tire I see is black. Cars, trucks, bicycles. Why black?
MomDaniel, because of a discovery made more than a century ago that made tires dramatically stronger. And the answer connects to one of the most surprising company histories you will ever hear.
DanielHmm, what company?
MomYou are going to love this one. It was Crayola.
DanielCrayola, the crayon company, is connected to… Why tires are black?
MomWe will get there. But first, what color do you think natural rubber actually is?
DanielIs it black?
MomIt is actually off-white. Natural rubber comes from latex in rubber trees, and latex is milky and pale. The very first car tires in the early 1900s were white or light gray. Early tires were also reinforced with zinc oxide, which kept them white. But those early tires wore out far faster than modern ones.
DanielSo, those early tires wore out much faster than the ones we use today.
MomAnd the reason for that difference is a single additive. Carbon black, a fine, dark powder made from burning hydrocarbons in a limited supply of air. At some point in the early 20th century, the exact history is a little murky. Manufacturers discovered that mixing carbon black into rubber transformed the material.
MomTires became dramatically stronger and more resistant to wear, heat, and degradation from sunlight.
DanielSo, the black color is not a design choice. It is a side effect of adding something that makes the tire work much better.
MomExactly. The black comes from the carbon black, and once manufacturers realized how much better reinforced rubber performed, it became a standard part of tire compounds. The funny thing is that the color we now think of as the natural color of a tire is really the visible signature of an ingredient added to the rubber.
DanielSo, black tires are basically a chemistry clue.
MomAnd now, Crayola. Binney & Smith, the company that created Crayola crayons in 1903, was already a major pigment manufacturer. One of its specialties was carbon black, and when the tire industry began using carbon black to reinforce rubber, Binney & Smith became one of its suppliers.
MomIn 1911, B.F. Goodrich, the tire manufacturing company, reportedly asked the company for an annual supply of a million pounds.
DanielSo, the company, making colorful crayons for kids, was also making black pigment for car tires.
MomCorrect! Crayons on one side, industrial carbon black on the other. Same company, two very different uses for pigment.
DanielAnd why did the white wall tire exist? I have seen those in old photos. Black tires with a white stripe around the outside.
MomEarly on, some tires combined black carbon reinforced tread with white rubber sidewalls. You will sometimes hear that manufacturers did this simply to save money by putting carbon black only where the tire touched the road. But the exact history is messier than that.
MomHistorical evidence suggests white walls soon became premium products, and eventually, a major fashion statement.
DanielSo even the history of the white wall is not as simple as it looks.
MomThe chemistry explains why black rubber took over. And fashion explains why people sometimes wanted some of the white back.
DanielDoes anyone actually know why carbon black makes rubber so much stronger? Like, what is actually happening at a molecular level?
MomUntil very recently, nobody fully knew. Carbon black has been used in tires for over a century. It clearly worked. But scientists still debated exactly why the reinforcement was so powerful at the molecular level. Then, in 2026, researchers at the University of South Florida published a study after running 1,500 computer simulations, totaling about 15 years of computing time.
MomThey found that carbon black constrains how rubber changes shape, when it is stretched. The rubber strongly resists the resulting change in volume, almost like the material is fighting against itself. And that helps explain the dramatic increase in strength.
DanielAmazing! We have been putting something in tires for over a hundred years, and only now have researchers produced a much clearer explanation of how it actually works.
MomAs one of the researchers put it, how is it that we have been using this for 80, 90, 100 years, and have not really known how it works? It has been through enormous trial and error, which is actually how a lot of engineering happens. Discover something works, use it, understand it much later.
DanielSo, every black tire on every car is proof that something can be enormously useful long before it is fully understood.
MomAnd the next time you see a tire, you are looking at a material whose reinforcing effect scientists spent decades trying to fully explain, that was discovered to be dramatically superior to what came before, and whose color is a direct record of the chemistry that makes it work.
MomSo, Daniel, what is one thing you are taking with you today?
DanielI love these pop quizzes, mom! Let's see, natural rubber is off-white, not black. Early car tires were often white or light-colored and wore out far faster than modern tires. Then manufacturers discovered that adding carbon black, a powder from burning hydrocarbons, dramatically improved the rubber's strength and resistance to wear, heat, and degradation from sunlight.
DanielThe black color is a direct result of the carbon black. The company behind Crayola Crayons, Binney & Smith, was also an important early manufacturer of the carbon black used in tires. I also remember that early black tread tires sometimes kept white rubber sidewalls, and those white walls eventually became a major automotive fashion.
DanielAnd amazingly, even after more than a century of using carbon black to reinforce rubber, researchers only produced a much clearer explanation of why the effect is so powerful in 2026.
MomThe black color of an ordinary tire is a chemical signature, not just a style choice.
DanielI am going to think about Crayola every time I look at a tire from now on.
MomTwo very different products. And one very interesting connection.
