Unnoticed low tyre pressures on runflats
Results 1 to 3 of 3
  1. #1

    savageian's Avatar
    Join Date
    Nov 2012
    Location
    Cumbria
    Posts
    1
    Car Specs:
    Year
    2009
    Model
    E87
    Engine
    123d
    Fuel
    diesel
    Thanks
    0
    Thanked 0 Times in 0 Posts


    Donate Please click the
    image to support
    BMWForums.info
    Click Here To Contribute To Our Site

    Unnoticed low tyre pressures on runflats

    Feeling a bit embarrassed because I haven't been checking my runflats tyre pressures. My excuse and reasoning is that I believed that the tyre pressure monitoring system would alert me to any problem.
    The fronts have worn on the outer edge (just as the last set had done, and others seem to experience as well) and after about 18k I had them replaced. The guy at the tyre place (Camskill in Whitehaven) told me that both front tyres were down to 14psi !!!!! Thinking logically now, i believe that the TPM system monitors the rotational speed of the wheel via the ABS system. A flat tyre will have a smaller rolling diameter and therefore rotate faster than the one on the other axle. However, if both are going down at the same rate there will not be a difference to measure and hence no alert.
    Since admitting this to some work colleagues it seems that i am not the only one. I will definitely be checking them regularly now.
    You might say that I should have noticed something with the ride being poor but in all honesty it wasn't. They are runflats after all but I would have thought the miles that i must have done on them at such a low pressure would have ruined them all together. The ride with the new set is obviously much tighter but not appreciably so. I am tempted to deflate them to around 14psi and see how they feel, just to confirm that Camskill's gauge is reading right!

    Anybody else had a similar experience?

  2. #2
    Got that WMD right here.
    BFI God you need to get out more!
    cforehead's Avatar
    Join Date
    Apr 2012
    Location
    North Devon-cestershire
    Posts
    7,485
    Car Specs:
    Year
    2006 & 1994
    Model
    E91 & 106 Rallye
    Engine
    N52 2996cc & TU2J2 1294cc
    Fuel
    Petrol & Petrol
    Thanks
    4,024
    Thanked 4,354 Times in 3,121 Posts


    As the sidewalls are so rigid you notice them going flat much less than conventional tyres. My TPMS seems quite sensitive, detects a drop of 5-10psi quite quickly but then I don't have run flats anymore either.

    You did very ​well to get them to 18k miles if they dropped as low as 14psi
    2006 E91 330i M Sport click
    2006 E87 130i M Sport SOLD click
    2009 E70 Xdrive30d M Sport SOLD
    2008 E92 335d M Sport SOLD
    click
    2002 E46 330 Clubsport SOLD click
    1994 Peugeot 106 Rallye click

  3. #3
    BFI Veteran
    jrfty's Avatar
    Join Date
    Apr 2012
    Location
    London
    Posts
    2,154
    Car Specs:
    Year
    2004
    Model
    E46
    Engine
    330ci
    Fuel
    V-Power
    Thanks
    910
    Thanked 1,272 Times in 895 Posts


    Quote Originally Posted by savageian View Post
    Feeling a bit embarrassed because I haven't been checking my runflats tyre pressures. My excuse and reasoning is that I believed that the tyre pressure monitoring system would alert me to any problem.
    The fronts have worn on the outer edge (just as the last set had done, and others seem to experience as well) and after about 18k I had them replaced. The guy at the tyre place (Camskill in Whitehaven) told me that both front tyres were down to 14psi !!!!! Thinking logically now, i believe that the TPM system monitors the rotational speed of the wheel via the ABS system. A flat tyre will have a smaller rolling diameter and therefore rotate faster than the one on the other axle. However, if both are going down at the same rate there will not be a difference to measure and hence no alert.
    Since admitting this to some work colleagues it seems that i am not the only one. I will definitely be checking them regularly now.
    You might say that I should have noticed something with the ride being poor but in all honesty it wasn't. They are runflats after all but I would have thought the miles that i must have done on them at such a low pressure would have ruined them all together. The ride with the new set is obviously much tighter but not appreciably so. I am tempted to deflate them to around 14psi and see how they feel, just to confirm that Camskill's gauge is reading right!

    Anybody else had a similar experience?
    I got myself this
    Award Winning Racex Race x RX0014 Tyre Pressure Gauge | eBay

    It's awesome and very accurate

    Johann
    Eibach Sportline springs, Powerflex bushes, 8.5j/10j 19" Matt black VMR V710s 235/265 Vredestein Ultralac Sessanta, All black badges, 35% tint, black front grille, lamin-x tint film on front & rear lights, 55W 7.5k HIDs, Orion V2 halo LED angel eyes, Cree reverse bulbs, 18SMD number plate lights, smoked side markers, keyhole delete, K&N panel filter, private plate, bwchiptune ecu remap. http://youtu.be/atvGNof4iB0

User Tag List

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •