Wheel sizing question

[HaloJ]

I'm a little confused with regards to tyre sizing. Two bikes by Trek the XO and the Pilot 2.1 have Bontrager SSR wheels. The XO runs 700x35s and the 2.1 runs 700x25s. My original understanding was that tyre size was controlled by the wheel size but the above example contradicts this. Could a kind sole explain this for me, please?

Thanks

Abs

 

[HLaB]

They're both 700mm rims but the 35mm is wider than the 25mm, nothing much to it really.

 

[MadoneRider1991]

they are both 700c wheeled bikes, the second part of the wheel size (x35 and x25) are the width of the wheel!

 

[RecordAceFromNew]

These tyres are for the same rim/wheel size, they are just of different width. A comprehensive explanation is here.

 

[HaloJ]

Ok, so a quick (possibly inaccurate) measure of my hybrids wheels shows the rims to be 19mm and going by Sheldon's charts that suggests I could "safely" put on a 700x28 tyre?

 

[potsy]

Ok, so a quick (possibly inaccurate) measure of my hybrids wheels shows the rims to be 19mm and going by Sheldon's charts that suggests I could "safely" put on a 700x28 tyre?

That's what I have and they are fine with 28's on there,wouldn't go any thinner though.

 

[HLaB]

Ok, so a quick (possibly inaccurate) measure of my hybrids wheels shows the rims to be 19mm and going by Sheldon's charts that suggests I could "safely" put on a 700x28 tyre?

That's my understanding of his chart at the bottom of Sheldon's page.

 

[HaloJ]

Cool! Thanks all! That's shattered my illusion that the wheel/rim forced a fixed tyre width. Like what I now know, though.

*ticks box "learn something new every day"*

 

[jimboalee]

Don't take a lot of notice of the '700' sizing. Is it a 622?

The inside measurement of the rim ( 19mm ? ) will safely take a 20mm tyre, a 20 - 622.

I've got MA2 rims 21mm inside and have 23 - 622 tyres. No probs.
I've got Bonty Race-X-lite with 22 - 622 tyres. Similarly, no probs.
I'm running 23 - 622 tyres on Alesa 21mm inside rims. NO PROBS.

 

[threefingerjoe]

Jimboalee...I'm with you on this one. I wish everyone would use the standard ISO tyres sizes. It really prevents confusion when you get into those different 26" sizes.

It's even hard to get some LBSs to understand and use the ISO numbers.