Totally bamboozled by tyre sizes.

[Encantador]

And I thought fitting a BBS02 to my Trek Hybrid was the hard part.

A rear puncture has me completely baffled. On inspection decided that tyre needed changing as well as tube. Tyre is a Bontrager and possibly many years old. Size says 32-622 700x32c, I purchased from Amazon a Marathon Plus of the same size, totally surprised when I tried to put it on and it basically fell off the other side and is obviously way too big for the wheel.

Had the rear wheel changed a while back, the old tyre was transferred to it. The markings on the new wheel say.... ETRO 622x19c….. 21/19c….. Alloy 606316.

I cant understand how the old tyre fitted and the new one doesn't and have no idea what size to order next.

Any help gratefully received.

 

[saneagle]

The important size is the rim outer diameter, which is 622mm for a 700c wheel. You should check it to make sure that's what you have, but if the tyre on it says 32-622, that's what it is. The other number is the tyre width in mm and doesn't really matter. Only the 622 has an influence on whether the tyre falls off. If your new tyre says 622, it should fit, so check what's written on it. That's the only info you didn't give us. maybe they sent you 28" which can be 635mm.

Marathon Plus will stretch and become useless if you lever them too hard. You need to put them on with the correct method, ideally without levers by getting 3/4 of the tyre into the well, then working the last bit into the well as soon as it's over the rim until the last bit pops over.

 

[Raboa]

This is from Schwalbe website, you can download the graph as a PDF.

Tire Dimensions

www.schwalbe.com

What width are your new tyres?

Which tire fits which rim?
The inner diameter of the tire must match the rim bead seat diameter. For instance, a tire size 37-622 fits on a 622 x 19C rim.

 

[Encantador]

Thanks for the replies.

The new tyre has the numbers ..... 32-622 28x1.25 700x32c
The inside rim of the wheel is 19mm

The whole new tyre just goes over the rim and off the back, not possible to squeeze the tyre together enough to get one rim to stay in the wheel, at least not without 6 hands. Measuring between the rims of the new tyre is about 45mm.

 

[saneagle]

Thanks for the replies.

The new tyre has the numbers ..... 32-622 28x1.25 700x32c
The inside rim of the wheel is 19mm

The whole new tyre just goes over the rim and off the back, not possible to squeeze the tyre together enough to get one rim to stay in the wheel, at least not without 6 hands. Measuring between the rims of the new tyre is about 45mm.View attachment 52454

You're measuring the wrong part of the rim. It's the diameter you have to measure not the width. What is the measured diameter 622mm or not?

 

[Encantador]

622 diameter looks about right. But trying to get the two rims of the tyre which are 45mm apart into the wheel where the space between the rims is 19mm looks impossible. What am I missing?

 

[soundwave]

i cant get my tyres on the rim on my own but i use cable ties to stop the tyre popping off the rim as i go round otherwise.

 

[Encantador]

Thanks, I have watched a few videos, the first bead seems to stay in the rim and the issue is to get the secone bead in all the way round. My problem is the first bead just falls off the wheel.

 

[saneagle]

622 diameter looks about right. But trying to get the two rims of the tyre which are 45mm apart into the wheel where the space between the rims is 19mm looks impossible. What am I missing?

You do one side at a time. That video above is not right for what you have to do so ignore it.
1. Pump a little bit of air into the tube, just enough to support it, not enough to expand it and place it inside the tyre.
2. Poke the valve through the hole and screw the retainer half way to stop it coming back out. Make sure that the tyre is the right way round if has direction arrows.
3. Pull one side of the tire over the rim and push the the tube into the rim. The first side always goes easily. you have to hold the first half of it in while you get the second side in, which is fiddly if you have a stiff tyre.
4. Starting at the opposite side to the valve, start rolling the tyre over the rim.
5. Work the rest of the tyre over, working in both directions so that the last bit is where the valve is.
5. When you get 75% of the tyre over, twist the 75% of that side of the tyre into the middle of the well.
6. Using your thumbs lever the next bit of tyre over the rim, then go round working the rest of that side into the well.
7. Repeat step 6 until the last bit pops over.
8. Put a small amount of air into the tube to create a bit of tension on the sides and use your thumbs to adjust each side of the tyre until the guide line is concentric with the rim.
9. Pump up the tyre.

 

[sjpt]

As others have said, it looks as if you've got the right size.
Try getting the first bead in all the way round, insert the inner and pump it up just a little. Then fit the second bead, being very carful not to pinch the inner.

Marathon Plus are usually very tight to fit, but I did have one once that was very loose and I never managed to fit it correctly. I fitted another to the same wheel later and it was tight but fairly easily doable. (Woosh XF07 622 700c front).

 

[Encantador]

You do one side at a time.

Appreciate that, but it is not possible when the first bead just falls off the wheel when you start to try and put the second bead in. The tyre is just too big.

Just seen a chart that suggests if the gap between the wheel rims if 17-19mm (mine is 19mm) the correct tyre size is 23-25c, my new tyre is 32c.

 

[Encantador]

As others have said, it looks as if you've got the right size.
Try getting the first bead in all the way round, insert the inner and pump it up just a little. Then fit the second bead, being very carful not to pinch the inner.

Marathon Plus are usually very tight to fit, but I did have one once that was very loose and I never managed to fit it correctly. I fitted another to the same wheel later and it was tight but fairly easily doable. (Woosh XF07 622 700c front).

Thanks. With one bead in all the way round the wheel there is a gap I can get my finger tips in hence why it just falls off the wheel......

 

[soundwave]

its either the wrong size or a dud tyre

 

[saneagle]

Thanks. With one bead in all the way round the wheel there is a gap I can get my finger tips in hence why it just falls off the wheel......

That's normal if you have a deep well.

I explained to you that you have to put the tube in the tyre first. It's to stop the first side going into the well causing the whole tyre to fall back off.

 

[Encantador]

Thanks for all the replies. I have tried with the tube in partially inflated, the gap is just too large and the tyre too rigid to try and hold one bead in the rim. I am leaning towards the wrong size or a duff tyre. I have ordered a 700x25c, if that doesn't fit I will take the wheel into the shop.

Thanks again.

 

[Brik]

Just seen a chart that suggests if the gap between the wheel rims if 17-19mm (mine is 19mm) the correct tyre size is 23-25c, my new tyre is 32c.

Most 700c wheels seem to be 19 mm wide, 45 mm wide tyres fit fine...

 

[Raboa]

This is from Schwalbe, they recommend 22mm to 24mm but the ETRTO standard says your size is ok.

 

[Bikes4two]

Thanks. With one bead in all the way round the wheel there is a gap I can get my finger tips in hence why it just falls off the wheel......

• I've just looked at the image you posted (below) and if as you say you have one bead in all the way around, then that tyre is wrong for that wheel.
• Now I now some rim styles are easier than others, but that gap looks too big to me.
• Marathon Plus are usually annoyingly tight, not loose (I gave all mine away as (a) they rolled like cra*p and (b) in the event of a puncture out on the road, took ages to get off/on, delaying all in the group)
• Have you done comparisons with the other wheel - dare you see if the Marathon fits on the other rim (the practice will do you good ).
• 

 

[saneagle]

The amount of gap you get to put your fingers under depends on the depth of the well in the rim. You can see that OP has a deep rim, so his gap can be quite normal. My 700c ones were the same as that. It was really difficult to get a start because the tyre is hard and keeps falling off until you can use the tube to hold it on.

MPs afre very difficult to fit on Brompton rims because they have no well. They normally fall on (and off) MTB rims.

Another problem you can get is that they're not supposed to be folded, but some sellers will fold them to put them in a smaller package for shipping. That can cause one part of the bead wire to expand so you can't line up the bead with the rim. The same happens if you use force to lever the tyre over the rim instead of using the coreect method.