Why No Explosion? The Science Behind Temperature and Pressure in Tires

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Discussion Overview

The discussion revolves around the relationship between temperature and pressure in tires, particularly why an increase in temperature does not lead to an explosion despite theoretical expectations based on gas laws. The scope includes theoretical considerations, practical implications, and some misunderstandings related to temperature scales.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant asserts that gas pressure varies directly with temperature, suggesting that a temperature increase from 2 degrees Celsius to 20 degrees Celsius should lead to a significant pressure increase in tires.
  • Another participant points out the need to use the Kelvin scale for accurate calculations, implying that the Celsius scale leads to incorrect conclusions about pressure changes.
  • A different participant mentions that the pressure increase would only be about 1.07-fold rather than the expected 10-fold, indicating a misunderstanding of the relationship between temperature and pressure.
  • One participant discusses the theoretical maximum air temperature after compression, noting that it would be much higher than 2 degrees Celsius and that actual temperatures would be affected by heat loss and material resistance.
  • Another participant emphasizes the importance of the gas equation in Kelvin, explaining that a tenfold increase in temperature would not correspond to the Celsius values presented.
  • There is a suggestion that the original poster (OP) may have misunderstood the temperature scale and that this misunderstanding is central to the discussion.

Areas of Agreement / Disagreement

Participants express differing views on the correct application of temperature scales and the implications for tire pressure. There is no consensus on the best explanation for why tires do not explode under the discussed conditions, and multiple competing interpretations remain.

Contextual Notes

Some limitations include the reliance on the Celsius scale for calculations, which may lead to incorrect interpretations of gas behavior. Additionally, assumptions about tire expansion and heat transfer are not fully explored, leaving some aspects unresolved.

Who May Find This Useful

This discussion may be of interest to those studying thermodynamics, gas laws, or practical applications of physics in everyday scenarios, particularly in relation to automotive safety and engineering.

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It is scientific fact that that if all else is held constant, the pressure of a gas varies directly with its temperature. In other words, if you have a gas in a sealed, insulated, rigid container and you double its temperature, its pressure will also double. If you triple the temperature, the pressure will triple, etc. This is not EXACTLY true, but it is close enough for the purpose of this teaser.

Why is it, then, that If I were to fill my tires with 32 psi of air on a day that is 2 degrees Celsius, the tires won't explode if the temperature later increases to 20 degrees Celsius (which would seemingly increase the pressure 10-fold to 320 psi, well beyond the capacity of most tires)?

Assume that the temperature of the air in the tire always matches the temperature outdoors: it starts at 2 degrees and ends at 20 degrees.
Also ignore the fact that the tires will expand.
 
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Something to do with the temperature scale, you need to find Kelvin for the answer.
 
Someone slashed your tire!
 
Science said:
Why is it, then, that If I were to fill my tires with 32 psi of air on a day that is 2 degrees Celsius, the tires won't explode if the temperature later increases to 20 degrees Celsius (which would seemingly increase the pressure 10-fold to 320 psi, well beyond the capacity of most tires)?

The pressure will only increase by about 1.07-fold instead of 10-fold.
 
The theoretical max. air temperature after compression is that calculated by adiabatic process and is much above 2deg.C. Considering heat loss to ambient and polytropic process, actual temperature reduces but still above 2deg.C. Further, filled air temperature need not be equal to that of ambient air due to the resistance of tube and tyre material.
 
can some one explain that ?
 
quark said:
The theoretical max. air temperature after compression is that calculated by adiabatic process and is much above 2deg.C. Considering heat loss to ambient and polytropic process, actual temperature reduces but still above 2deg.C. Further, filled air temperature need not be equal to that of ambient air due to the resistance of tube and tyre material.

Although I'm sure this makes sense to people who know more about this than me, I think the basic reason is explained by AntonVrba and wave.

Gas equation takes into account temperature in Kelvin's scale pV = nRT, so tenfold increase wouldn't be 2°C -> 20°C but 275 K (= 2°C) to 2750 K = (2477 °C). But I think you'd have to worry about your tires melting then, not bursting :)
 
Anton and wave have both hinted at the answer.

The OP was wrong to use the Celsius scale. He should have used Kelvin. Doubling 2 degrees Celsius gives 277 Celsius, not 4 degrees Celsius.

In any case, he's either left or been banned, so there's no helping some people...
 
I got a PM from the OP inviting me to join another forum. Thought it was kind of strange. Suspect the OP spam'd all of us good folks here on PF.
 

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