Increase in Tyre Pressures

Discussion in 'Tech/Mech General' started by Zigisla, Jun 16, 2016.

  1. Zigisla

    Zigisla Funster

    Joined:
    Oct 24, 2015
    Messages:
    1,003
    Likes Received:
    1,176
    Location:
    Fareham, Hants
    Not with standing the fact that I run at 80 psi - not weighed yet and seems like Continental will say 80 anyway; but when on a longish run my tyre pal indicates that my pressures have increased to between 88 & 90 psi and sets off the warning buzzer - 10% according to the instructions I believe.
    Is this increase normal and the warning should be set higher, or do they seem to be increasing too much at a higher than normal px and needs investigating? This is all 4 tyres rising in px and not just 1, no warning of over temping and as yet not thought about dropping the px yet.
    Experience and words of advice welcome as always.
     
    • Thanks Thanks x 1
  2. Baycott

    Baycott Funster

    Joined:
    Nov 6, 2013
    Messages:
    6,315
    Likes Received:
    10,605
    Location:
    East Sussex
    I had exactly the same result and was surprised to see the pressure increase by 10lb or more:Eeek:
    I found that the warmer the weather the higher the increase. I have just set my tyrepal alert higher.
     
    • Thanks Thanks x 1
  3. Revolvor

    Revolvor Funster

    Joined:
    Oct 8, 2014
    Messages:
    157
    Likes Received:
    116
    Location:
    Wiltshire
    My tyre pressures typically rise by less than 10 psi, as indicated on my Tyre-Pal. The only time the alarm has gone off was in July last year, on the hottest day of the year, when pressures and temperature rose considerably as we came down the M1. We pulled into a Service area and waited a few hours for cooler weather.
     
    • Thanks Thanks x 1
  4. denisejoe

    denisejoe Funster Life Member

    Joined:
    Aug 6, 2014
    Messages:
    1,154
    Likes Received:
    837
    Location:
    Isle of Sheppy
    That's the reason they say check when cold
     
    • Like Like x 1
  5. kevan

    kevan Funster Life Member

    Joined:
    Jan 18, 2014
    Messages:
    367
    Likes Received:
    315
    Location:
    Herne Bay
    I have snooper tyrepilot. tyres are rears 80 psi front 70 psi usually goes up to about 10 psi when hot just set alarm to a bit higher am told this is quite normal.
     
    • Thanks Thanks x 1
  6. Richard Birkett

    Richard Birkett Funster

    Joined:
    Nov 25, 2014
    Messages:
    67
    Likes Received:
    38
    Location:
    Essex
    I had the same issue and contacted tyrepal who advised increasing the upper limit.
     
    • Thanks Thanks x 1
  7. mikebeaches

    mikebeaches Funster

    Joined:
    Feb 22, 2010
    Messages:
    960
    Likes Received:
    629
    Location:
    Bristol
    Yes, I was surprised just how much the tyre temperature readings increased on the van when travelling at speed, especially when in the Mediterranean region with high ambient temps.

    Believe it is absolutely normal, so you can adjust your Tyrepal alarm levels accordingly.
     
    • Thanks Thanks x 1
  8. dave newell lvs

    dave newell lvs Trader-Vehicle Services

    Joined:
    Oct 31, 2008
    Messages:
    2,515
    Likes Received:
    3,321
    Location:
    Telford, Shropshire
    If you look up "Boyle's Law" you will find out why your tyre pressures go up when driving. This law is the sole reason a diesel engine works.

    D.
     
    • Like Like x 2
    • Informative Informative x 1
  9. Zigisla

    Zigisla Funster

    Joined:
    Oct 24, 2015
    Messages:
    1,003
    Likes Received:
    1,176
    Location:
    Fareham, Hants
    Aware they would go up, but it was the amount they went up concerned me though
    if the volume of the air inside remains constant and doesn't decrease why does pressure increase.
     
    Last edited: Jun 16, 2016
  10. dave newell lvs

    dave newell lvs Trader-Vehicle Services

    Joined:
    Oct 31, 2008
    Messages:
    2,515
    Likes Received:
    3,321
    Location:
    Telford, Shropshire
    Look up Boyle's law, that will explain all.

    D.
     
    • Like Like x 3
  11. matamoros

    matamoros Funster

    Joined:
    May 15, 2008
    Messages:
    2,271
    Likes Received:
    3,423
    Location:
    Ex Rochdale now Tavira, S. Brittany & Europe
    If you drive for long periods with the hot sun on one side of vehicle then one side will be higher than the other as well:)
     
  12. Zigisla

    Zigisla Funster

    Joined:
    Oct 24, 2015
    Messages:
    1,003
    Likes Received:
    1,176
    Location:
    Fareham, Hants
    No it doesn't. unless I am failing to see how the volume of the air decreases as you drive along. It also does not explain why pressure increase by approx 10 psi.
     
  13. treetops1

    treetops1 Funster

    Joined:
    Feb 25, 2013
    Messages:
    887
    Likes Received:
    993
    Location:
    yorkshire
    Heat increases the pressure.
     
  14. Gorse Hill

    Gorse Hill Funster

    Joined:
    Feb 2, 2013
    Messages:
    1,403
    Likes Received:
    1,605
    Location:
    Stretford
    Your looking up the wrong Boyle (y)
     
  15. scotjimland

    scotjimland Funster Life Member

    Joined:
    Jul 25, 2007
    Messages:
    28,934
    Likes Received:
    25,574
    Location:
    .
    All gasses expand as the temperature rises.. expansion increases pressure .. and visa versa
     
  16. Zigisla

    Zigisla Funster

    Joined:
    Oct 24, 2015
    Messages:
    1,003
    Likes Received:
    1,176
    Location:
    Fareham, Hants
    How many are there. Can you point me in the right direction.
    I am well aware of temp and pressure but the "boyles law" I looked up is for volume and pressure where temp is constant.
     
  17. dave newell lvs

    dave newell lvs Trader-Vehicle Services

    Joined:
    Oct 31, 2008
    Messages:
    2,515
    Likes Received:
    3,321
    Location:
    Telford, Shropshire
    Boyle's law details the mathematical relationship between pressure temperature and volume in a closed vessel. You no doubt read the Wikipedia stuff but that doesn't actually cover it all, Wiki says P1V1=P2V2 but the true formula is P1V1T1=P2V2T2. Pressure volume and temperature are inherently linked in a closed vessel.

    In a tyre the volume stays pretty much the same but as it is driven over a road surface it heats up and sooner or later that heat is passed into the gas inside. This rise in temperature while volume stays relatively stable leads to an increase in pressure which is proportional to the temperature increase.

    As I said earlier, it is the sole reason a diesel engine actually works!

    D.
     
    • Like Like x 1
    • Informative Informative x 1
  18. Zigisla

    Zigisla Funster

    Joined:
    Oct 24, 2015
    Messages:
    1,003
    Likes Received:
    1,176
    Location:
    Fareham, Hants
    Whilst I will not die in a ditch over this it must be pointed out that the relationship which includes a veritable temp is Charles law. A combined gas law has the equation of P1V1/T1 etc so if you can point out another site not wiki that states your formula great. If not I think it is more likely the combined gas law not boyles's.

    Anyway. It does seem that 10psi is the norm(y)
     
  19. dave newell lvs

    dave newell lvs Trader-Vehicle Services

    Joined:
    Oct 31, 2008
    Messages:
    2,515
    Likes Received:
    3,321
    Location:
    Telford, Shropshire
    What is a "veritable temperature" please?

    D.
     
  20. Zigisla

    Zigisla Funster

    Joined:
    Oct 24, 2015
    Messages:
    1,003
    Likes Received:
    1,176
    Location:
    Fareham, Hants
    Bloody predictive text. Variable. :rolleyes:
     
    • Like Like x 1
Loading...

Share This Page