Tyre sizes?

[Skyedriver]

OK, I come from a more simple time.
Tyre sizes nowerdays seem to be 26", 28", 29" 622, 700, and heaven knows what else.
Was after spare tubes for my Cannondale (you know, the one with the recall on the front forks)
Is there a dummies guide to bike tyres?

[Fastpedeller]

Yes - don't go by the dummy sizes (29er really grates with me!) Look for the ETRTO size on the wall of the tyre - as an example a 700 tyre of 25mm width will be 622 - 25. An old 27" tyre 1 1/4 inch wide will have 630 - 28. Much more accurate than 'marketing sizes' and ensures it will fit.
Hope that helps.
ETA - If buying tubes you may find the tube boxes don't have all the relevant info, but certainly for the latest 'marketing sizes' anything 26.5 inch, 27 inch 28 inch 29 inch will likely be 700 x width - width being the critical dimension, and will often be a range eg 700 x 28-32mm. As an inner tube expands, it isn't hyper important, but you won't want to use 700 x 17-22mm in a 45mm tyre, but at a push if there was nothing else available you could use a 38mm tube which will expand enough (certainly if you've a puncture and that's the only way to get home.

Edited by Fastpedeller on Monday 20th April 23:19

[gazza285]

Very stretchy, inner tubes. The last time I built up a 29er I couldn’t find my box of inner tubes. I did find some old 26x1.75 tubes, so I used them instead, just blew them up until they were a big enough diameter and stuffed them in, then let them down again to get the tyre bead seated. Been like that for eighteen months now.

As for road bike tyres, I buy 700x25 and use them in everything from 23 on my old Vitus to the 38 on the commuter. They don’t quite stretch to a 29x2.35 though.

[Simes205]

OP you left out 650b or 27.5!

[Master Bean]

You have 35mm tyres on your CAADX so this is what you want. Presta valve and 700 28-35.

https://www.wiggle.co.uk/lifeline-wide-road-inner-...

[Skyedriver]

Fastpedeller said:

example a 700 tyre of 25mm width will be 622 - 25. An old 27" tyre 1 1/4 inch wide will have 630 - 28.

Edited by Fastpedeller on Monday 20th April 23:19

There you go...a 700 tyre is a 622...

[Skyedriver]

Master Bean said:

You have 35mm tyres on your CAADX so this is what you want. Presta valve and 700 28-35.

https://www.wiggle.co.uk/lifeline-wide-road-inner-...

Thanks

I was looking for a tube for the bairns Islabike on 26" tyres, most places were out of stock.
managed eventually from Sigmasport.

[Fastpedeller]

Skyedriver said:

Fastpedeller said:

example a 700 tyre of 25mm width will be 622 - 25. An old 27" tyre 1 1/4 inch wide will have 630 - 28.

Edited by Fastpedeller on Monday 20th April 23:19

There you go...a 700 tyre is a 622...

Thus emphasising the need to use the ETRTO size ie 622 as your go-to measurement - this is the bead seat diameter and is the definitive measurement, any other 'size' leads to confusion.

[Brads67]

Fastpedeller said:

Yes - don't go by the dummy sizes (29er really grates with me!) Look for the ETRTO size on the wall of the tyre - as an example a 700 tyre of 25mm width will be 622 - 25. An old 27" tyre 1 1/4 inch wide will have 630 - 28. Much more accurate than 'marketing sizes' and ensures it will fit.
Hope that helps.
ETA - If buying tubes you may find the tube boxes don't have all the relevant info, but certainly for the latest 'marketing sizes' anything 26.5 inch, 27 inch 28 inch 29 inch will likely be 700 x width - width being the critical dimension, and will often be a range eg 700 x 28-32mm. As an inner tube expands, it isn't hyper important, but you won't want to use 700 x 17-22mm in a 45mm tyre, but at a push if there was nothing else available you could use a 38mm tube which will expand enough (certainly if you've a puncture and that's the only way to get home.

Edited by Fastpedeller on Monday 20th April 23:19

All very good, but really apart from old retro bikes, their are only 700c , 27.5 and 29 to worry about , everything else is an oddity.

41 yrs fitting bicycle tyres and never even heard of ETRO numbers.

[Fastpedeller]

Brads67 said:

Fastpedeller said:

Yes - don't go by the dummy sizes (29er really grates with me!) Look for the ETRTO size on the wall of the tyre - as an example a 700 tyre of 25mm width will be 622 - 25. An old 27" tyre 1 1/4 inch wide will have 630 - 28. Much more accurate than 'marketing sizes' and ensures it will fit.
Hope that helps.
ETA - If buying tubes you may find the tube boxes don't have all the relevant info, but certainly for the latest 'marketing sizes' anything 26.5 inch, 27 inch 28 inch 29 inch will likely be 700 x width - width being the critical dimension, and will often be a range eg 700 x 28-32mm. As an inner tube expands, it isn't hyper important, but you won't want to use 700 x 17-22mm in a 45mm tyre, but at a push if there was nothing else available you could use a 38mm tube which will expand enough (certainly if you've a puncture and that's the only way to get home.

Edited by Fastpedeller on Monday 20th April 23:19

All very good, but really apart from old retro bikes, their are only 700c , 27.5 and 29 to worry about , everything else is an oddity.

41 yrs fitting bicycle tyres and never even heard of ETRO numbers.

Mine 43 years - those 2 years must be critical . ETRTO is the best way - just look at some tyres, it's definitive.
https://www.tredz.co.uk/help-advice/guides-reviews...

[Brads67]

Fastpedeller said:

Mine 43 years - those 2 years must be critical . ETRTO is the best way - just look at some tyres, it's definitive.
https://www.tredz.co.uk/help-advice/guides-reviews...

I found that guide but really it is no less accurate than normal sizing. Same number regards wheel size with a different number for widths. ?

I can't see how it is more accurate ? happy to be taught somit new mind.

[Fastpedeller]

Brads67 said:

Fastpedeller said:

Mine 43 years - those 2 years must be critical . ETRTO is the best way - just look at some tyres, it's definitive.
https://www.tredz.co.uk/help-advice/guides-reviews...

I found that guide but really it is no less accurate than normal sizing. Same number regards wheel size with a different number for widths. ?

I can't see how it is more accurate ? happy to be taught somit new mind.

You are correct - I made the mistake of posting link I hadn't looked at, but expected to be good

This one is much better
https://cyclocamping.com/blog/2015/08/01/what-do-s...

[Skyedriver]

Brads67 said:

Fastpedeller said:

Mine 43 years - those 2 years must be critical . ETRTO is the best way - just look at some tyres, it's definitive.
https://www.tredz.co.uk/help-advice/guides-reviews...

I found that guide but really it is no less accurate than normal sizing. Same number regards wheel size with a different number for widths. ?

I can't see how it is more accurate ? happy to be taught somit new mind.

Every day's a school day, I'm learning all the time, I'm 67 later this month, unless my ignorance and stupidity get the better of me.

[Brads67]

Or worse lol. Thats even more confusing , it even states that Inch sizes are more prevalent.


I do understand that it would be more accurate, but it seems to be an almost unused system, know mainly to tyre size geeks !

No offence mind.

Most of the sizes quoted, like 27", touring sizes etc are barely used now and could only be found on vintage bikes.

[Fastpedeller]

Brads67 said:

Or worse lol. Thats even more confusing , it even states that Inch sizes are more prevalent.


I do understand that it would be more accurate, but it seems to be an almost unused system, know mainly to tyre size geeks !

No offence mind.

Most of the sizes quoted, like 27", touring sizes etc are barely used now and could only be found on vintage bikes.

Inch sizes (or the use of them) is more prevalent - if only people (including retailers) would use the ETRTO system there would be no confusion!