Car tyre pressure

Discussion in 'Physics & Math' started by russell2002, Jul 18, 2003.

  1. russell2002 Registered Member

    Messages:
    3
    I have a question which despite many hours on google I am unable to find the answer,

    Say you have a car with 4 wheels, the correct pressure as advised by the car maker is 35 psi in each tyre.

    You, for whatever reason, want to to put smaller tyres (lower profile) onto the original alloy rim.

    As its the tyre pressure which is suporting the cars weight, with a tyre which has a lower internal volume, would you need a different tyre pressure,

    Regards,

    Russell.
     
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  3. Pete It's not rocket surgery Registered Senior Member

    Messages:
    10,167
    The pressure and weight supported are unrelated to the volume of the tires. The area of the tires in contact with the ground is the relevant variable.

    I'd be contacting the tire manufacturer.
     
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  5. mirage Registered Member

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    29
    keep in mind pressure is a density. if you take a stick of butter, and find that it is x psi and then you cut it in half. you measure the half and you find that it is still x psi. make sense? however you have other things to worry about if your go lower profile. your speedometer will be off as well. it's generally best to stick to OEM specs, IMO
     
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  7. On Radioactive Waves lost in the continuum Registered Senior Member

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    Shouldn't it say what pressure to put right on the tire?
     
  8. mirage Registered Member

    Messages:
    29
    that number isn't always accurate. rim design and car weight comes into play.
     
  9. russell2002 Registered Member

    Messages:
    3
    Assuming the tyre pressure is their to maintain the correct shape of the tyre, I agree the pressure should not needed to be changed.

    Can anyone tell me how a car makes decides on the PSI needed ?
     
  10. russell2002 Registered Member

    Messages:
    3
    Sorry for the typo -------

    How does a car manufacturer decide on the PSI needed for a given car.
     

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