With the exception of some children's vehicles, most vehicles have black tires. You'd be hard-pressed to find samples of Goodyear or Michelin tires in any color other than black at a tire store.
However, natural rubber is closer to an off-white hue, and early model cars also had lighter colored tires. Early tire manufacturers often added zinc oxide to natural rubber to strengthen it, resulting in white tires. But at some point, tire manufacturers decided to switch to dark colors. Why is this?
Jalopnik auto journalist David Tracy posed the question while visiting the Ford Factory Museum in Detroit, where he spotted a Ford Model T (production began in 1908) with white tires. Tracy then raised questions about the color shift with Michelin, which said that when manufacturers started adding carbon black to tires around 1917, the tire color has changed since then.
Carbon black is not intended for decorative purposes. In fact, carbon black (elemental carbon produced by the incomplete combustion of gases or oils and collected as particulate matter) can enhance tire durability, in part by blocking damaging UV rays that can cause rubber to crack, and by improving road grip at this point. In addition, carbon black increases the tensile strength of the tire, making it more resistant to road wear.
Older tires that have not been treated with carbon black can go up to 5,000 miles before needing to be replaced. Meanwhile, tires made with carbon black can run 50,000 miles or more.
It’s worth noting that there was another reason for the tire’s color shift: World War I led to a shortage of zinc oxide because the country needed it to make ammunition. As a result, carbon black at that time became the preferred reinforcement material for tire companies (although zinc oxide still plays a role in tire manufacturing today).
So, is tire color evolution over by then? Pretty much. Earlier, some companies tried to control production costs by adding carbon black only to the tread, and inadvertently created whitewall tires with white sidewalls and dark treads. This two-tone look remains popular among today's classic car collectors.