Very high tyre pressures

Discussion in 'Australia and New Zealand' started by Claude, Aug 23, 2003.

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  1. Claude

    Claude Guest

    Putting 100 PSI in my hybrid's tyres even though the tyre says 75 is recommended. Means I don't have
    to pump the bloody things up so often. Of course it makes the ride harder. Does anybody know if
    there's a serious downside to this practice (I weigh 100 kgs)?
     
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  2. Joel Mayes

    Joel Mayes Guest

    In article <[email protected]>, Claude wrote:
    > Putting 100 PSI in my hybrid's tyres even though the tyre says 75 is recommended. Means I don't
    > have to pump the bloody things up so often. Of course it makes the ride harder. Does anybody know
    > if there's a serious downside to this practice (I weigh 100 kgs)?
    >

    If you seriously overinflate the tubes I imagine the tyres could be forced off the rims.

    --
    | Joel Mayes | Linux and OpenBSD | /"\ ASCII ribbon | Accordionist | | \ / campaign against |
    | Musician | My PC, My Rules | X HTML mail and | Music Teacher | | / \ postings |
     
  3. John Dwyer

    John Dwyer Guest

    "Claude" <[email protected]> wrote in message
    news:[email protected]...
    > Putting 100 PSI in my hybrid's tyres even though the tyre says 75 is recommended. Means I don't
    > have to pump the bloody things up so often.
    Of
    > course it makes the ride harder. Does anybody know if there's a serious downside to this practice
    > (I weigh 100 kgs)?
    >
    I once destroyed a tyre by overinflating it. The threads under the tread started to break up and it
    gave a very rough ride. I do not recommend overinflating a tyre.

    John Dwyer.
     
  4. Claude <[email protected]> wrote in message news:[email protected]...
    > Putting 100 PSI in my hybrid's tyres even though the tyre says 75 is recommended. Means I don't
    > have to pump the bloody things up so often.
    Of
    > course it makes the ride harder. Does anybody know if there's a serious downside to this practice
    > (I weigh 100 kgs)?

    Possibly an increased chance of a blowout, and more vibration coming through to your body, hammering
    your wrists, arse and legs. Your frame might not last as long due to the sharper shocks hitting it.
    Bicycles are designed for a particular pressure, and increasing it way beyond that could lead to all
    sorts of problems.

    Report back in a few weeks if it's still ok!
    ---
    DFM
     
  5. Cody

    Cody Guest

    "Claude" <[email protected]> wrote in message
    news:[email protected]...
    > Putting 100 PSI in my hybrid's tyres even though the tyre says 75 is recommended. Means I don't
    > have to pump the bloody things up so often.
    Of
    > course it makes the ride harder. Does anybody know if there's a serious downside to this practice
    > (I weigh 100 kgs)?

    Over inflated tyres tend to crack along the walls but I have never had one fail on me or at least
    they wore out before they failed. I don't do it now but I used to overinflate my 27" by 1 1/8 tyres
    by a simliar amount to you. it gave me a better and faster ride (I am about 90kg) .
     
  6. Gary K

    Gary K Guest

    Some tyres when constantly overinflated eventually bubble, or a fat portion appears giving a bumpy
    ride. You might be lucky though.

    Claude <[email protected]> wrote:

    > Putting 100 PSI in my hybrid's tyres even though the tyre says 75 is recommended. Means I don't
    > have to pump the bloody things up so often. Of course it makes the ride harder. Does anybody know
    > if there's a serious downside to this practice (I weigh 100 kgs)?
     
  7. Kingsley

    Kingsley Guest

    On Sat, 23 Aug 2003 05:41:46 +0000, Claude wrote:

    > Putting 100 PSI in my hybrid's tyres even though the tyre says 75 is recommended. Means I don't
    > have to pump the bloody things up so often. Of course it makes the ride harder. Does anybody know
    > if there's a serious downside to this practice (I weigh 100 kgs)?

    Hey, just get some tyres rated to the pressure you want to inflate them too. It's not worth
    splitting your wig on the concrete for the sake of correct inflation. While a catastrophic failure
    is probably (?) unlikely, why take the risk ?

    -kt
     
  8. Jonas

    Jonas Guest

    > 100 PSI in my hybrid's tyres ..Does anybody know if there's a serious downside to this practice (I
    > weigh 100 kgs)?

    hmm, i've done quite a few kms touring around bits of the world now, and have seen many people
    over-inflate tyres. the side wall tends to go 1st, unless there is something else wrong with the
    tyre, eg a small slit. the pressure rating is just a number a company sticks on the side where the
    statistical probability of the trye blowing under that pressure is low enough for them not to be too
    worried about people complaining about their tyres.

    last year in canada, i met a few die-hard 'kamikaze tyre' fans who love el cheapo tyres whose
    quality varies so much. it might say 35-50psi on the side, but you might well be able to get it up
    to 80-100 psi with no problems. you won't find out until you get there. my experience is that not
    too long after you get there (somewhere between seconds and weeks) when you do, your tyre sidewall
    will go. by the same token, the kamikaze tyre may explode under its rated pressure too! that's half
    the fun. i reckon it's more like a waste of rubber.

    i have a suspicion that better tyres are generally more quality controlled, and principles of
    equivalence suggest that you really can't go much past their pressure rating, but you can almost
    definitely get at least to the pressure rating. but, the same thing happens - the side wall blows.

    when the side wall does blow, your tube will expand so rapidly through the hole that you will
    probably be left with a hole too big to patch. there's nothing really catastrophic about it except
    that you have to add more rubbish to the world. obviously, stop asap, don't ride on your rims, and
    if it's the front tyre, your steering will be bad. after seeing way too many tyres blow, i would
    recommend getting tyres that are 'rated' to at least near the pressure you want. and try not to go
    over that pressure (or always stick at least 5psi underneath of a half decent tyre, and never blow
    the side wall - it's worked for me for the last 25000km). if you're heavy, use slightly wider tyres.
    i've seen people touring with a combined rider+load+bicycle weight of around 150kg, but just be
    careful of the bumps.

    hope this helps
     
  9. Marty

    Marty Guest

    "John Dwyer" <[email protected]> wrote in message news:<[email protected]>...
    > "Claude" <[email protected]> wrote in message
    > news:[email protected]...
    > > Putting 100 PSI in my hybrid's tyres even though the tyre says 75 is recommended. Means I don't
    > > have to pump the bloody things up so often.
    > Of
    > > course it makes the ride harder. Does anybody know if there's a serious downside to this
    > > practice (I weigh 100 kgs)?
    > >
    > I once destroyed a tyre by overinflating it. The threads under the tread started to break up and
    > it gave a very rough ride. I do not recommend overinflating a tyre.
    >
    > John Dwyer.

    Over inflating your tyres can cause your rims to split. Fairly common apparently on large volume
    tyres that are over pressurised.
     
  10. amirm

    amirm New Member

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    I use Continental Super Touring 2000 which are rated at 85 psi max. I inflate them to anything between 85 and 100. They have done 4000 km now, and I can see very tiny cracks on the side walls of the rear tyre. Not sure they are because of the tyre pressure, or just signs of natural wear and tear. However, I cannot feel the difference in terms of the ride quality and drag between 85 and 95 psi. Before these, I had Specialised tyres rated at 100 psi. First I kep them at 80 psi. Not much comfort anyway, so I decided to pump them up to 100 psi. After 2000 km, I had to replace them under warranty because all thread and sidwall surfaces were falling apart (got Conti's instead). The conti's have much better ride quality and lower drag at 85 than the Specialised's at 100 psi.

    By the way, depending on the structure of the tyre, overinflation can harm rims. I had to replace two spokes with my specialed tyres once I started to inflate them to 100psi.



     
  11. amirm <[email protected]> wrote in message news:[email protected]...
    > Claude wrote:
    > > Putting 100 PSI in my hybrid's tyres even though the tyre says 75 is recommended. Means I
    > > don't have to pump the bloody things up so often. Of course it makes the ride harder. Does
    > > anybody know if there's a serious downside to this practice (I weigh 100 kgs)?
    >
    > I use Continental Super Touring 2000 which are rated at 85 psi max. I inflate them to anything
    > between 85 and 100. They have done 4000 km now, and I can see very tiny cracks on the side walls
    > of the rear tyre. Not sure they are because of the tyre pressure, or just signs of natural wear
    > and tear. However, I cannot feel the difference in terms of the ride quality and drag between 85
    > and 95 psi. Before these, I had Specialised tyres rated at 100 psi. First I kep them at 80 psi.
    > Not much comfort anyway, so I decided to pump them up to 100 psi. After 2000 km, I had to replace
    > them under warranty because all thread and sidwall surfaces were falling apart (got Conti's
    > instead). The conti's have much better ride quality and lower drag at 85 than the Specialised's at
    > 100 psi.
    >
    > By the way, depending on the structure of the tyre, overinflation can harm rims. I had to replace
    > two spokes with my specialed tyres once I started to inflate them to 100psi.

    That's probably related to the increase in shock that is transfered to the spokes. I imagine
    the cracks that are occuring are also cause by an increased transferral of shock to the rim
    from the road.

    Why did you over-inflated your tires to 95 psi if it makes no difference to the ride?
    ---
    DFM
     
  12. amirm

    amirm New Member

    Joined:
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    Good point!

    Since tyres loose pressure, I try to save on checking/pumping frequency. At the same time, I wouldn't like to go below 80psi. What I didn't mention in the previous posting is that although I cannot feel a tangible difference between 85 and 95 psi, I can feel a noticeable difference in drag in lower pressures (such as 70 psi vs 85 psi).

    So by keeping my tyres a little over-inflated, I remain in the green zone in-between pumpings. Apparently, ~10 psi above nominated rating is not having a huge adverse effect on the ride quality (comfort) and tyre's life.


     
  13. D. Advocate

    D. Advocate Guest

    "Claude" <[email protected]> wrote in message
    news:<[email protected]>...
    > Putting 100 PSI in my hybrid's tyres even though the tyre says 75 is recommended. Means I don't
    > have to pump the bloody things up so often. Of course it makes the ride harder. Does anybody know
    > if there's a serious downside to this practice (I weigh 100 kgs)?

    I've had the wire beads break when I overinflated some tyres (KABOOM!). Actually, I was right on
    the limits of the things (150psi) so I've never inflated tyres that high since (or used wire
    beaded tyres).
     
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