There’s a lot of thought that goes into choosing tires for your car/truck: Do you need a whole new set, or will one or two do the trick? Do you need to swap out your current summer tires for a season-appropriate set? Do you plan to go off-road or hit the race track?
There is one thing that likely never comes to mind, though: What color tires should I buy? Sure there are white walls, and the occasional white or red letters, but they are all otherwise black. Why is that?
The short answer has to do with World War I and crayons. When cars were first rolling down the few proper streets and rough national roads in the United States, tires were mostly white because rubber is naturally nearly white. All manufacturers needed was a mold or two, and plenty of rubber to pour in them.
Of course, tire making was just as much in its infancy as building the cars themselves, so there was a pretty steep learning curve all around. One main issue, as cars became less toys for the rich and more daily transportation, was making those tires last for more miles. Vulcanization of rubber certainly helped, as did improved tire construction techniques, and chemical advances like the introduction of zinc and magnesium oxide to the rubber.
And then, WWI broke out. Those oxides were needed to make brass and propel bullets into the bodies of enemy soldiers, but the burgeoning auto industry still needed tires, especially for vehicles heading toward the front lines Europe. What was going to give the tires their needed strength and durability?
The Binney and Smith chemical company, makers of Crayola Crayons, had the answer at their pen tips: carbon black. The substance, commercialized as a pigment by processes like the one patented by Edwin Binney in 1891, is basically soot from burning gas and was originally used for writing and printing. It wasn’t until 1904 that S.C. Mote discovered the strengthening properties of the substance while working for the India Rubber, Gutta Percha, and Telegraph Cable Company. This black carbon pigment was being used to give rubber a dark color, but its other properties were not immediately known to tire manufacturers.
The story goes that BF Goodrich had introduced a special series of tires dubbed “Silvertown,” named after the Silvertown rubber district in London, where the India Rubber, Gutta Percha and Telegraph Cable Company was located. The manufacturer used some of Binney and Smith’s carbon black to tint their tires black like telegraph cables, but in so doing, bolstered the strength of the infused rubber. After discovering the increased wear resistance, BF Goodrich put in an order for 1 million pounds of carbon black. Binney and Smith responded by founding the Columbian Carbon Company just to produce carbon black, and they eventually developed and patented the process of producing the substance in pellets.
This happened in a few years before the start of World War I. Once those other chemicals were siphoned away for the war effort, the carbon black tires popularized by BF Goodrich spread to every tire manufacturer. The chance discovery of carbon black and its superiority to zinc or magnesium oxide meant tires would never go back to being white (other than whitewalls, of course).
If you’re interested in learning more about why tires are black, this detailed piece from Jalopnik breaks down the convoluted history in much greater detail.Tags: Chilton Auto Answers, history, manufacturing, tires, WWI