Here’s Why Tires are Black
It’s one of those facts we all take for granted — the sky is blue, the grass is green, and tires are black. However, cream-colored natural rubber doesn’t bear much resemblance to the rubber we burn on the road. And primitive tires, like those seen at the dawn of automotive history, were that same shade of off-white. Check out the wheels on this old buggy:
So why did tires change? Well, there were a few reasons. During the early days of tire manufacturing, companies figured out that adding zinc oxide both strengthened rubber and made it a brighter shade of white. However, with the outbreak of World War I, zinc oxide was in high demand for use in munitions. Thus, tire makers needed an alternative additive.
Know Your Tires: Check out this tire guide
In 1917, tire manufacturers made the switch by adding carbon to rubber instead of zinc oxide.
Aside from the dwindling supply of zinc oxide, there were a few other reasons to make the switch. Carbon strengthened tires while adding a few more advantages, compared to the old formul. With carbon, tires boasted more tensile strength and a better road grip. It also protected them from sun damage, which caused white tires to crack.
The proof was in the numbers. Before the addition of carbon, tires lasted 5,000 miles before needing to be replaced. The new, improved carbon-infused tires lasted over 50,000 miles.
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Source: Mental Floss