Good Morning,

My 4 yr old received an old bike from one of the neighbors today, unfortunately both tires are flat and cracked and there may be damage to the inner tubes as well.

I am not able to go to a bicycle store to have them replaced. So i figured I would try and replace both myself, as I found some DIY youtube videos on how to do the process.

The challenge I am facing now is finding the correct parts to do it.

On the tire itself it says a size of 18 x 1.95, I was able to find a tire for this size on Amazon (Amazon Link). The original tires on my daughters bike look different though, a little research told me the original tires are mountain bike tires, by the looks of it. But my daughter will only be riding her bike on the road/side walks so I am assuming this tire I found on Amazon will be sufficient.

Now I am trying to find a tube for this tire, but cannot find a tube with a 18 x 1.95 size. I am even thinking that maybe I am looking for the wrong size tube for this tire size.

I have never changed a bike tire nor a tube in my life and would appreciate any assistance in locating a compatible tube for this tire.

Also if someone could tell me if this type of tire that I found on Amazon is suitable for the road/side walks.

Appreciate any help I can get.

Kind Regards, Andrea

3 Answers 3


For a four-year old, who will be riding around your backyard or at the park, any tire that holds air will be fine. There's no MTB-specific tyres that small.

Those tires will be totally fine on pavement and will work well enough on dry grass too.

The tyre specs in your link are for an 18" tyre (that's the measurement across the whole wheel) which is 1.95" in width, which is the horizontal width of the tread approximately.

18" is unusual - is it possible that it reads 16" ?

Most tires have a ETRTO code - I suspect your current tyres will say something like 47-305 on the sidewall (or possibly 305-47 which is the same thing just reversed.) It means 47mm wide tyre, and 305mm across.

The bigger number has to match your replacement tyre, but the width has some leeway.

Could you please check your old tyres for the ETRTO code, and once you have that, the replacement must match. Your Amazon link doesn't show a ETRTO code sadly, but there will be many others that do.

Your other option is to simply inflate the existing tyres and see if they hold air. Depends if they're just faded, or rotted to useless. If there are bits of rubber falling off, they're definitely in need of replacement.

As for inner tubes, the ones on your bike now may be okay even if the tyres are rotted. You will need to add some air and see if they hold overnight.

If you do choose to buy tubes as well, there are similar numbers to match in terms of size, but the tolerances are larger.

You'll need to get two tubes of course, but the box will cover a larger range of possible sizes. See the front of this one which covers 340,349 and 355 sizes with the same tube.

enter image description here

Lastly you need to have the same type of valve as the old tubes - its 99% likely you will need a Schrader valve, same as on a car tyre.

  • A lot of kids bikes have MTB styling, including the tyres. A little grip isn't a bad idea as they may well be riding on dirt paths, but takes extra effort, so switching to smoother tyres is probably a net benefit.
    – Chris H
    Apr 16, 2020 at 11:39
  • 1
    IMHO the tube in the image is rather unusual since it covers a wider variety of nominal rim diameters than usual (16" and 18") but has a very narrow range of widths. Apr 16, 2020 at 14:46
  • 1
    @cbeleitesunhappywithSX yes but "16 to 18 inches" sounds like a lot more than it really is. 340mm to 355mm is only 15mm, so just over half an inch of real difference. Silly imperial measurements being so imprecise :-\
    – Criggie
    Apr 16, 2020 at 14:48
  • Criggie, I know (that's why I put the "nominal" in). More to the point of this question, I'd expect a typical tube to cover a width range of maybe 1.25" - 1.75" or 37 - 47 mm. (Or 47 - maybe 57 mm, 1.75 - 2.25"). I'd think a width range of only 9 mm is very narrow (but then the tube is anyways too narrow for OP's 50 mm tire). Apr 16, 2020 at 14:55
  • Good Evening, thank you all so very much. I wasn't expecting such thorough detail with the answers. All of this information has helped me greatly. BTW i searched the tire again on both sides and there is no ETRTO code on it. The only information written on the tire is "YIDA", "Inflate to 35 P.S.I" and "18 x 1.95". But with everyones comments I think I am good now.
    – Andrea
    Apr 17, 2020 at 4:02

To expand a bit on Criggie's answer:


  • In my experience, kid's bikes don't come in as specialized rim widths as say the choice between a road bike and an MTB.
    I'd expect tire widths from 1 3/8" (37mm) to 2" (50 mm) to fit, maybe even 2 1/4" (57 mm).

    1.75" (47mm) is a standard size where I am, and it is close to your 1.95". In case you have not yet ordered the linked tires, you may be able to get 1.75" ones locally.

  • If there are lots of thorns around where you are, you may want to consider a puncture proof tire.
    (I became fairly expert in repairing tubes from age 8 or so on growing up in a rural area before puncture proof tires became a thing...)


  • Tubes are sold for a range of widths (and sometimes even for a range of rim diameters). Typical width ranges would be e.g. 1.25" - 1.75" and 1.75" to 2.25".
    The "narrower" ones are a bit lighter, but IMHO that doesn't matter for a kids bike. The "wider" ones are sometimes a bit more robust and in my experience they may also be better at holding the air.
    I wouldn't expect difficulties with a (new) tube that is sold for slightly wider tire tires (say, 1.5" tube with 1.75 - 2.25" tube), but I would not put the tire on Criggie's picture for 1.4" width into a 1.95" width tire. (I've tried and the result were frequent punctures.)


  • Where I am both Dunlop and Schrader (car) valves are common. They use the same valve hole diameter in the rim, so if you find (locally) tubes only with one of the valve types that doesn't matter.

  • You need the right kind of pump though (but many pumps can do both, either one side or the other or by turning around the rubber sealing). There are also adapters.

  • If you get a Dunlop valve, I recommend to get a "flash valve" insert - they are much easier to pump since less pressure is lost across the ball valve than with the rubber hose.
    Schrader valves are also harder to pump. This doesn't matter with a foot pump or a compressor, but with a hand pump an adapter that depresses the spring and uses a ball valve instead makes life easier.

    For an adult, this doesn't matter much, but it may be the differnce between your kid being totally helpless and soon being able to pump their bike to a pressure that allows them to ride.

About changing tires:

  • Using tire levers for taking off the old tire is in my experience pretty safe. But for putting on the new tire, I've punctured the hose in the past even with proper tire levers, but never when working with my hands only.

    I therefore avoid tire levers when putting on tires, and this gets much easier by

  • having some pieces of string/rope/velcro tape/zip tie to tie down the part where the tire is on already. This prevents it from slipping off again when the hard last part comes and it will also keep it tied into the lower inner part of the rim bead which makes it as loose as possible for slipping the last part over the rim wall. Here someone did this IMHO rather excessively, I usually start with one tie right beside the valve, and then do 2 more ties with the tire 2/3 or 3/4 on.

  • Tire montage paste (in German colloquially: Reifenseife, literally tire soap) as used for car/truck tires also helps. Since this is sold in buckets that are much larger than you need, you could either try to get a small amount from a local tire workshop or try whether liquid dishwashing soap works as well (haven't tried).

    The paste is brushed onto the sidewall of the tire and it help it slipping over the rim wall.

  • I literally just found two valve inserts in a small paper box in my cupboard and wondered what they might be. They were Dunlop ones (never used this valve type in my life), one with a rubber hose and one of the flash type. I am able to blow through the flash one with my mouth but completely unable to do so through the other one. Apr 16, 2020 at 18:46
  • @VladimirF: yes, that's typical. Apr 16, 2020 at 22:19

You can fold a larger tube to fit it for the smaller diameter tire or rim. At least for a bicycle that will be rolling slower than you walk and does not need much pressure either. With just one fold, air will come anyway from another side.

I do not know, there may be reasons against doing so for an adult bicycle that moves at usual speeds.

  • If your tube is longer than the tyre requires it is likely to fold double making you feel a bump in each turn of the wheel. Better spread the tube as well as you can in the tyre, the tube will spread a bit better that way. (I ride 20" wheels and there are two types of tubes with that size and sometimes I had the wrong one, I learned by experimenting.)
    – Willeke
    Dec 4, 2021 at 11:31

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