Why don't my 24 inch tyres fit my 24 inch wheels,

[ishaw]

Wanted some wider tyres as the stock ones were 1 inch on my new airnimal. Bought some new ones but the don't fit the rim, the circumference seems way too small, not even close. Any ideas why as there is no indication on the site I got them from that there are different 24 inch standards.

 

[mechanical_vandal]

Have a look at the tyres page on the SJS website and you'll get an idea of just how many versions there are for each imperial "standard".

You'd be much better using the metric measurement which you should find on your old tyres.

 

[ishaw]

My old tyres (well new) are panaracer pasela and say 24 x 1 on them so I assumed that 24 x 1.75 would be the same, but wider. I'll see if there are other markings but it makes the term 'standard' a bit of an oxymoron.

 

[ishaw]

The original tyres say 1600x25c, new tyres have no other markings other than 24x1.85. Not much to go on re. new tyres sadly.

 

[one-eyed_jim]

Wanted some wider tyres as the stock ones were 1 inch on my new airnimal. Bought some new ones but the don't fit the rim, the circumference seems way too small, not even close. Any ideas why as there is no indication on the site I got them from that there are different 24 inch standards.

Have a read of Sheldon's tyre sizing page:

http://sheldonbrown.com/tyre-sizing.html

The Airnimal Joey comes with two rim options, 520mm ETRTO and 507mm ETRTO, both designated 24", but incompatible. You must have the model with 520mm ETRTO rims. Your new tyres are probably 507mm ETRTO. The sizes are probably moulded into the tread or sidewall somewhere, but they can be hard to spot.

You may have trouble finding anything much broader to fit your rims. There used to be a 28mm Panaracer Pasela in 520mm, but its no longer made. Georgena Terry sells a 24" 520-32mm tyre, but they're expensive, and you'd probably have to import them. Changing to 507mm rims would be an option, but not a cheap one.

 

[ishaw]

Thanks, very helpful if not a touch depressing as it will make tyre options a tad limiting. I did check the new tyres carefully and there are other markings but nothing g significant relating to size. My airnimal was supposed to come with the wider marathons so maybe they are an option.

I was contemplating new wheels at some point as I've gone all disc and the airnimal rims are rim brake ones, any thoughts on some replacement rims as I have some xt and pro 2 evo hubs doing nothing and could get them built up.

 

[one-eyed_jim]

I was contemplating new wheels at some point as I've gone all disc and the airnimal rims are rim brake ones, any thoughts on some replacement rims as I have some xt and pro 2 evo hubs doing nothing and could get them built up.

It's not a market I know much about, I'm afraid. I'm still stuck in the retro, rim-braked world!

My airnimal was supposed to come with the wider marathons so maybe they are an option.

From the Spa Cycles website, it looks as though the Marathons come on the 507mm version. Have you been sent the wrong model by mistake?

 

[ishaw]

It could be that I've got the wrong wheelset but it's the right model. Odd that they would sell slightly different wheel variants, surely that's not cost effective?

Would these tyres be any use?

http://www.chainreactioncycles.com/mobi ... -prod24628

They seen to have an ETRTO range bigger than 520. I'm still a little confused by this tbh, but I guess it explains why some tyres are hard to get on to a rim when others slip on easily. I'd not want it to be a loose fit bit until your post, I didn't know about all this ETRTO and that 24 inch doesn't mean 24 inch. It's a learning curve I was not expecting.

 

[mjray]

The reason inch decimal sizes and inch fractional sizes differ is that fractional is English and decimal is usually USA and they measure them in different ways. Always stick to the ISO markings now: two numbers with a dash between. One is width and the other is bead seat diameter. I think the order varies between rims and tyres and the ideal tyre is 1.8 times the rim width.

 

[ishaw]

Spent some time googling and found this tyre which is listed as a 25 inch but has an ETRTO of 520. Adding to my confusion, but would this be the right or wrong size?

http://www.sjscycles.co.uk/mobile/schwa ... prod37402/