I understand that carbon is black so we end up with black tires. But black has max conductivity, so wouldn’t there be a possibility of overheating and bursting? Why don’t we have coat it with coloring agents so it’s with a color that’s thermally less conductive?
In: Physics
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Most of the heat in a tire is generated inside of it from compression or at the tread from friction. More heat conductivity encourages heat being dumped into the environment instead of building up in the tire. Incident heat from sunlight, etc. isn’t a big deal by comparison.
Maybe it would taint the streets?
>wouldn’t there be a possibility of overheating and bursting?
Car tires can cope with pressures far higher than their actual recommended running pressure. This isn’t a problem.
Bear in mind that when you drive, friction from the road and from the deformation of the tire with each rotation already substantially increases the tire temperature without difficulty.
It just isn’t a concern.
Rubber tires started out white because that was the color of natural rubber. But natural rubber is soft and they wore out quite quickly. Eventually a guy named **Charles Goodyear** invented vulcanized rubber, a way of treating rubber with sulfur and other chemicals to create cross-linked molecules that made the rubber much tougher. As you probably picked up by now he used this invention to make better tires.
Part of the ingredients in these better tires are 20-30% carbon, specifically a form of fine particulate carbon called “carbon black”. This makes the tires stronger, more conductive to heat helping to cool the treads (we *want* them conductive), and protects the tire from UV damage from sunlight. It also makes them emphatically black. If you want them another color you had better paint them because you can’t make them out of 30% carbon black and expect any other dye or pigment to show up while having anything left for, you know, **tire**.
I somewhere read that red and blue tires (probably other colors too) were used for gangs to mark the territory by doing donuts and burnout’s on the roads.
And at one point colourful tires were banned in the us.
Way back it the aughts, I worked for an ad agency with Michelin as a client, and when we asked this very question, in addition to the answer already mentioned about vulcanized rubber processing, they said that other colors just get really dirty really fast, and they look terrible when they are dirty.
In short, two reasons: it adds cost for a useless feature, and it wouldn’t be stable over time.
And there are colored car tires, but they don’t last very long, and I’m not even sure if they’re street legal (not due to color but the tire itself).
All the other answers, plus they make colored tyres too, used primarily for burnouts. The smoke they generate has a colored dye added to it, and they offer somewhat lesser traction. Some brands selling then are Highway Max and Kumho.
Watch this Good Ol’ TG video about these tyres: youtu.be/zyAVy20mEUA
If this interests you, you should look up the very short lived illuminated tires. They were lowkey rad as heck.
https://www.hagerty.com/media/automotive-history/why-goodyears-bright-idea-for-illuminated-tires-didnt-shine-for-long/
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