# Why tyres are in black colour?

Tyres used in every automobiles are balck in colour why? and why they dont use other colours?

## Replies

• Ramani Aswath
It does not show muck much. Carbon black is used as a filler, which among other things improves thermal properties.
• serpents egg
Hey me ramani...read ur views on the pressure velocity thing..need to know wat happens in case of nozzles were the pressure should increase due to thee change or reduction in the area..but the velocity of fluid increases TRUE..but wat about pressure ..cause pressure-f/a
• Ramani Aswath
serpents egg
Hey me ramani...read ur views on the pressure velocity thing..need to know wat happens in case of nozzles were the pressure should increase due to thee change or reduction in the area..but the velocity of fluid increases TRUE..but wat about pressure ..cause pressure-f/a
If the nozzle is open to atmosphere the pressure will be automatically atmospheric pressure.

The total energy in an element of fluid in a continuous system has to be constant assuming no friction in pipe.
In real systems there is wall friction, which leads to a pressure drop required to maintain a particular flow rate. However, this can be neglected in short length systems like the nozzle. Because there can be no accumulation or depletion of fluid, when the diameter decreases the velocity has to increase to maintain the same flow rate at all cross sections.
Conservation of total energy requires that the pressure decreases to maintain the total energy constant.
• serpents egg
True,sir..
But still i am unable to get the answer to my question about wat actually happens at microscopic level inside the fluid flow that due to the reduction in the area the velocity shoots up,followig the continuity ie a1v1 =a2v2.......but ,..wat about the preesure ..according to the conservation of energy bernoulis which says that the total head has to remain constant so the presssure has to reduce to maintain the toatal head constant.....but how does it happens should i assume due to the increase in the velocity the contact time between the fluid particles and the wall decreasess or the flow bwcomes more laminar due to increase in velocity///sir plese throw some light on the above statements if u agree.
• KSS Manian
Blvn Lakshman
Tyres used in every automobiles are balck in colour why? and why they dont use other colours?
I think its similar like a black umbrella. Related with heat.
• zaveri
Blvn Lakshman
Tyres used in every automobiles are balck in colour why? and why they dont use other colours?
Good Idea ! from now onwards why don't we think of painting our tyres white .
• Ramani Aswath
There is a different take on this issue:

• Ramani Aswath
serpents egg
throw some light on the above statements if u agree.
It is better to keep threads in same locations to avoid tangled discussions. I shall try to clarify your points in the original P-V thread.

You are reading an archived discussion.

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