Replace Bike Tyre or Tube?

expatOz on 25/03/2022 - 13:07
Last edited 25/03/2022 - 13:12

Hi,

I have an eBike with a Continental Max Tyres 700x42C (42-622). Lately the front tyre start losing air too frequently so I removed the tube and tried to check for any leaks in water but as I was pumping air the tube suddenly burst.

Now I'm not sure what exactly was the issue since it couldn't have been a leak otherwise it wouldn't burst I suppose. So should I get a new tyre or a tube?

Also I can't seem to find 700x42C online, would 700x40 work or does it have to be the exact same? Same for the tube, would 700x40C work or how does it this all work?

Thanks!

Sports & Outdoors Bicycle Accessory

Comments

  • [Deactivated] on 25/03/2022 - 13:10
    +4

    not sure how it would be losing air if the inner tube didn't have a hole somewhere, it might have been a small leak, which was enough to make it lose air but still enough to hold pressure and when you pumped it, the leak was the weak point where it burst.

    replace the inner tube and see how that goes, i doubt there is a problem with the tyre.

    • expatOz on 25/03/2022 - 13:14

      Oh ok. I can't find 700x42 tubes online though, any idea where I might get one? Also I can see the new tyre (comes with tube I imagine?) costs just 25-30 whereas a tube is 10-15 so wondering why not just replace the tyre instead of risking it with a tube, and then going for a tyre replacement?

      • [Deactivated] on 25/03/2022 - 13:19

        https://www.99bikes.com.au/tube-700c-x-32-43mm-schrader-valv…

        that says 42C in the title, but then goes on to say 35 in the description. i don't know what the 42C stands for, but i've found a fair few on amazon that are 700 x 35 - 47

        i don't know if those are suitable or not, not sure why there is a range.

        i wouldn't bet on the new tyre coming with a tube unless it is specifically mentioned that it does come with a tube

        • expatOz on 25/03/2022 - 13:31

          Thanks, I was just looking at that one. Now the only question is which size value 48 or 60mm. My current tyre doesn't say anything about it.

          • Seraphin7 on 25/03/2022 - 13:33

            @expatOz: Unless you've got deep carbon rims, 48mm is what you're looking for. Either way, just measure against existing.

      • trongy on 25/03/2022 - 16:18
        +3

        Inner tubes are like socks, they stretch a certain amount so you don't need a precise fit.

    • franco cozzo on 25/03/2022 - 13:29
      +3

      leaks dont 'burst'…the OP overinflated

      • [Deactivated] on 25/03/2022 - 13:42
        +2

        it could have had a small leak which was leaking air slowly, when he inflated it the leak was a weak point in the tube.

        • franco cozzo on 25/03/2022 - 13:43
          +1

          not really how it works from my experience…over inflation is what causes a tube to suddenly burst

      • expatOz on 25/03/2022 - 14:09

        Forgot to mention I overinflated in the first place because the pump just wasn’t reading the pressure .. stayed on 0. Faulty valve?

        • franco cozzo on 25/03/2022 - 14:18
          +2

          you wont get a reading unless you inflate the tube within the tyre and properly reseated on the wheel
          never inflate a tube to maximum out of the tyre…it will explode/split if you go too far. only inflate partially if checking for location of the leak

          • expatOz on 25/03/2022 - 14:31

            @franco cozzo: Wasn’t getting a reading even before removing the tube. But good point thanks

          • lunchbox99 on 25/03/2022 - 15:38
            +3

            @franco cozzo: Lol, I suggest OP takes the bike to shop. If they don't know this, they clearly haven't got a clue.

            • expatOz on 25/03/2022 - 16:12

              @lunchbox99: True, indeed I didn't have a clue and it burst because of my stupidity Well, thats one way of learning things. :D

  • brotherfranciz on 25/03/2022 - 13:28
    +4

    First off, I would carefully check the tyre to make sure there isn't anything lodged in it. There could be a small sharp object that penetrated through and stuck in the tyre itself. Obviously, be careful when you do this and try not to poke around too hard with your bare hands.

    So the numbers themselves:

    700 is the standard wheel size (the other common size is 650B, which is a smaller wheel). 42C is the width of the tyre: the bigger the number, the wider the tyre. A typical road bike tyre width ranges between 23 and 28, whereas hybrid and mountain bikes typically have wider tyres of 32 or more.

    Tyres generally don't come with tubes so you need to buy them separately. Some retailers sell bundles though.

  • franco cozzo on 25/03/2022 - 13:30
    +1

    get a new tube, check for embedded debris in the tyre ….fit & inflate paying attention to tyre max PSI

  • Seraphin7 on 25/03/2022 - 13:31
    +3

    The tube obviously had a leak somewhere … if it didn't it wouldn't be losing air!

    It's unlikely the tyre has ant material issues as these are usually far more obvious, such as deformation. That said, always run a cloth around the inside of the tyre when changing a tube to clear out ant grit/microshards that may be the cause of tube puncture.

    Here's one example of a tube that may be suitable for you.

  • Drakesy on 25/03/2022 - 13:31
    +1

    Well
    If it was a fast leak you can check the tyre by running your hands along the inside and feeling for anything sharp.
    If it's a slow leak the puncture might be too small to be discernable.

    In many cases i'd do the check, put a new tube in (provided the tyre isn't worn) and seen how you go. Tubes are only about $10 anyway.

    If that fails new tyre time.

    • franco cozzo on 25/03/2022 - 13:38

      sometimes you need to do a visual inspection too…flexing the tyre as you inspect the outer makes this easier to find small pieces of embedded glass or metal which you can remove with a small jewellers screwdriver or similar. you might not be able to 'feel' these on the inner wall

  • tsunamisurfer on 25/03/2022 - 13:52
    +1

    The leak may have been in the valve not the tube itself but thats moot now.

    The 42 refers to the number of millimetres of the diameter of the tube, the fatter the tube the more weight it can handle (as required with an ebike), and the LESS PSI required to inflate it.

    With tubes you do not need to get an exact 42c again, 40 is fine. My rim and tyre can handle from 25 - 32, the stock one was 28.

    Pay attention to the Max PSI of the tyre / tube.

    Inflate slowly, did you use an electric pump?

  • expatOz on 25/03/2022 - 13:57

    Aha thats what I suspected too .. a leak in the valve itself.

    Used a manual pump.

    • franco cozzo on 25/03/2022 - 14:07

      pretty rare…most slow leaks are an embedded piece of glass/metal in the tyre that creates a tiny puncture hole in the inner tube. thats why its important you check the tyre for debris as its very likely youll put in a new tube and get another slow leak straight away if you dont find whats causing it

      if you want to check the valve…inflate and submerge in water…if you get bubbles from the valve you know its the source

      • expatOz on 25/03/2022 - 14:09

        Hmm did try that no bubbles from the valve. :(

        • franco cozzo on 25/03/2022 - 14:15

          so slow leak in the tyre/tube…do what i have described, dont over inflate and youll be good

  • Euphemistic on 25/03/2022 - 15:38
    +2

    Tyres don’t come with tubes. The size is 700c (rim diameter) x 42 (tyre width in mm). Get a 700xAA-BB tube, where AA represents the narrowest tyre it’s designed to fit and BB is the widest tyre it will fit. Make sure the range between AA and BB suits your tyre. You can use tubes that are a little outside the range in a pinch, but its not recommended.

    When you reinstall the tyre and tube locate the tyre brand/logo next to the valve. That way when you get another puncture you can take note of where the leak is and inspect the tyre in the correct vicinity rather than having guess where it might be.

  • Anj1n on 25/03/2022 - 19:17

    Maybe watch a few more you-tube videos?
    Just a few psi is about all you would need to inflate a tube to check for leaks in water.
    Choose the correct valve, presta or schrader.
    Presta valves can be a bit tricky to inflate.
    Do inspect the inside of the tyre carefully for thorns etc. before reusing.
    Be careful you don't pinch the new tube when placing the tyre back on, easy to do.
    Your puncture would be more than a slow leak to require replacing the tyre.
    After you have changed five or ten on the side of the road it does get easier.

  • backpaqer on 26/03/2022 - 09:53
    +1

    If your tyre has good tread, you probably wouldn't need to change it. The exceptions are… If the tyre is very old and starting to show signs of cracking on the sidewall - replace it. When repairing a flat, you inspect the tyre carefully to look for glass/sharp objects embedded in the tyre. For a slow leak sometimes this can be a fine piece of wire that is almost impossible to see and feel, you need to run your fingers carefully along the inside surface of the tyre (the side your tube touches) and feel for anything that snags your skin.

    If you can find the location of the puncture on the tube, it quickly narrows down where you need to look on the tyre (if you haven't removed the tyre from the rim)… Or if you have, it's a good idea to install the tyre with a visible mark (logo etc,) aligned to where the tube valve stem goes through the rim to help find punctures. When inflating a tube to check for the leak you don't need to pump it up much, just enough to have shape. Then hold a section of tube under water and stretch the tube to put pressure on the air in the tube and also make the hole bigger making it much easier to find a slow leak. Also sometimes the leak can even be in the valve itself.

    Given that I usually buy tubes in bulk for about $5 each and patches usually cost $1 each (cheaper in bulk) I usually throw a tube and put in a new one.

    Getting a replacement tube, as others say, there's generally a range of fit. I run 700x19 and 21, 23, 25… The tubes I buy are all the same size and fit all those tyre widths. A 700x40 will fit a 42 no problems.

    • Euphemistic on 26/03/2022 - 10:45

      Given that I usually buy tubes in bulk for about $5 each and patches usually cost $1 each (cheaper in bulk) I usually throw a tube and put in a new one.

      This is not the ozbargain way. Patches are cheap and effective. I’ve repaired hundreds of punctures successfully (something like 26 one week near Dubbo with all the catheads). Some of my tubes have had up to 6 patches.

  • 82norm on 26/03/2022 - 10:11

    Is the tube a presta or schrader valve? If Schrader it’s easier to take it to a servo to pump. That said you can get an adapter to fit a presta to schrader valve.

    • Euphemistic on 26/03/2022 - 10:43

      Used to be easier to go to the servo. Nowadays they have those auto ones that are built for filling car tyres to 30psi and not suited to the small volume of bike tyres.

      • md333 on 26/03/2022 - 12:16

        The auto ones work fine on bike tyres, despite the warning labels.

        • Euphemistic on 26/03/2022 - 12:23

          I’ve used them too, but you need to be aware that you can’t put them on and wait for the right pressure. The volumes they use are too high for bike tyres. Ive found its ok if you are ready to disconnect quickly once the tyre is firm.

          • md333 on 26/03/2022 - 15:51

            @Euphemistic: I admit I haven't tried it on 19mm race tyres, but I've had no problem with a big variety 28mm+ tyres down to 12" balance bikes. Definitely pays to be aware and keep an eye on it but I haven't had to intervene yet.

  • Waltervp on 26/03/2022 - 12:48

    Easiest way to find a leak is still with a bucket of water. Don't need much air in tyre at all and will see bubbles straight away. Can also use a sponge with detergent and wipe on tyre and you'll see the bubble forming on the hole even without a bucket.

    Inner tube sizes are very flexible but the fitting has to be done with care. Like others say ensure the cause of the puncture is actually gone first by feeling the inside. Some people even put some baby powder on the inside to minimise friction. But also by putting the tyre back on the rim an amateur can easily puncture the new tube.

    My suggestion is to stop at a bike shop and let them do it for a bit more. Well worth it!!!

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