Tyre Pressure Confusion

bazmcg
bazmcg Posts: 95
edited August 2009 in MTB workshop & tech
I'v recently bought a digital tyre gauge so I'd know the pressure in my tyres and be able to play around with them. I have my tyre pumped up rock hard but the gauge is saying it's only at 20psi. The magazines reckon your tyre pressure should be between 30-40 psi. Do I have a faulty gauge?

Comments

  • Daz555
    Daz555 Posts: 3,976
    20psi is quite soft so if you say they are rock hard then yes, I'd say your gauge is faulty - or you are not seating it properly when you connect it to the valve to check pressure.
    You only need two tools: WD40 and Duck Tape.
    If it doesn't move and should, use the WD40.
    If it shouldn't move and does, use the tape.
  • kangaroo
    kangaroo Posts: 1,199
    borrow a track pump with a gauge, local bike shops will usually let yo use theres for free. and compare the pressures with that.
    what are brakes for again
  • bazmcg
    bazmcg Posts: 95
    Does the type of tube you are using make a difference, can all tubes/tyres be pumped up to 40psi?
  • kangaroo
    kangaroo Posts: 1,199
    I'm not sure, but i think its more to do with the tyres than the tube, i have 2.3 tyres on and the tube is something like a 2.2 but the people at the bike shop assured me that it wont make any difference and will be lighter than having a larger tube in there.
    it hasn't been more puncture prone, so I'm guessing there right
    most tyre should have there max psi on the side wall, but i think that they could all go up to 40psi
    what are brakes for again
  • .blitz
    .blitz Posts: 6,197
    If the tyre feels like a firm orange, the pressure is about right.
  • bazmcg
    bazmcg Posts: 95
    Ok so I borrowed a track pump with a gauge and the highest I can get the trye is 27psi. The tyre is rock hard. On the sidewall it says recommended pressure is between 35-65 psi. There is no way the tyre will go up to 35 psi. The tube will explode if I put any more air in. How do you guys get them pumped up to 40psi?
  • Tank-slapper
    Tank-slapper Posts: 968
    What does the gauge read up to?
  • nicklouse
    nicklouse Posts: 50,673
    sounds like a couple of faulty gauges or a weak operator :wink:
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Tank-slapper
    Tank-slapper Posts: 968
    Hope you are not reading the bar scale. 27 bar = 391 psi!
  • The Rookie
    The Rookie Posts: 27,816
    What valve are you using, Presta valves can be a pain if your using an adaptor as they are shut so the pressure in the adaptor is not the same as the one in the tube. Even without an adaptor they are usually closed. Schrader are easy!

    Simon
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • Daz555
    Daz555 Posts: 3,976
    bazmcg wrote:
    Ok so I borrowed a track pump with a gauge and the highest I can get the trye is 27psi. The tyre is rock hard. On the sidewall it says recommended pressure is between 35-65 psi. There is no way the tyre will go up to 35 psi. The tube will explode if I put any more air in. How do you guys get them pumped up to 40psi?
    If your tyres really are 'rock hard' then they are not at 27psi - the reading you are getting is wrong (or you have very weak hands :wink: ). I run about 38-40psi and I would not describe my tyres as rock hard at all.
    You only need two tools: WD40 and Duck Tape.
    If it doesn't move and should, use the WD40.
    If it shouldn't move and does, use the tape.
  • bazmcg
    bazmcg Posts: 95
    It's presta valves. The gauges go up to 100 psi. The tyres are 2.1 panracer ciders.
  • Skonk
    Skonk Posts: 364
    I'm using cinders on my i-drive and I run them at about 45psi and i've never had any issues getting them to that pressure.

    Using a Topeak Jo Blow pump.
    Canyon Spectral AL 9.0 EX
    Planet X RT90 Ultegra Di2
  • paul.skibum
    paul.skibum Posts: 4,068
    If they are hard under your hand they are alright - I wouldn't stress the pressure too much.

    I dont bother with tyre pressures - just go by feel. But I have used a mates track pump before and thought my tyres felt higher than the reading - same on a foot pump. My road tyres on my commuter read soemthing like 40 but are pretty much as hard as the tarmac!
    Closet jockey wheel pimp whore.
  • Skonk
    Skonk Posts: 364
    The problem is if you have the pressure too low, the tyre can lose grip on the inside of the rim and allow the rim to spin inside the tyre.

    If the tube stays with the tyre then the valve can get ripped out of the tube (happened to a m8 of mine).

    Would have to be pretty low on pressure though.
    Canyon Spectral AL 9.0 EX
    Planet X RT90 Ultegra Di2

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