The rubber that tires are sourced from is a milky white color, but carbon black is added to the rubber as a stabilizing chemical compound and makes the tire black. Carbon black is combined with other polymers to create the tire's tread compound.

When did tires become black?

Tracy posed the question of the color transition to Michelin, which informed him that tires changed color when manufacturers began adding carbon black around 1917. It wasn't for cosmetic purposes.

What does carbon black do for tires?

Adding carbon black avoids electrostatic charging and helps to conduct heat away from certain hot spots on the tire, specifically in the tread and belt areas. This reduces thermal damage on the tire and extends its lifespan.