Tyres and Tubes sizes

Andy54057

Appologies if this has been sked a thousand times before but my front tube went on the valve yesterday, I'd bought a spare but its bigger (or so it seems) and even though I've got it into the wheel and tyre inflated and fitted, I don't trust it to ride on the road...

Wheel size is: 622x15c Ksyrium Elite

Tyre size is: 700x23c (622x23)

Old tube size is: 700x18/25c

New (and current tube) size is: 700x20/28c (27 x 3/4'-1 1/8')

Questions being is it safe to ride in this configuration or will it just go pop, I've been using a turbo trainer so I'm not putting anything through the front, but in order to get out on the road I need someone a bit more in the know to help me out...

Cheers in advance

Andy

ollyridesfirst

This is fine....622 is actually the same size as 700C - 700C is just the french way of doing things (that is taken as standard now) and the 622 was brought in to try and standardise things....

Your tube should also be fine as the 20/28c bit means anything in between...so 23c tyre...

hope this helps

geoff93

Its fine, they can sometimes seem bigger because its just rubber, and rubber expands.

Andy54057

Thanks chaps,

Also with the wheels being 622x15c does the 15c bit refer to the width of the rim as its obviously not the diameter of the wheel...?

geoff_ss

622 mm is the diameter of the tyre bead (or the seat in the rim). So-called 27" wheels are 630 mm in diameter at the rim seat.

For some unknown (to me!) historical reason 700c was used to identify tyres with a 622 mm bead. The 'c' means a tyre height of 39 mm which gives an overall wheel diameter of 700mm (622 + 2x39) Overall wheel diameter was considered important because it has an effect on the gearing. Remember the whole reason some of us refer to gears in inches dates from the time penny-farthings were defined by the diameter of the wheel in inches.

Of course, for fitting purposes the only thing you need to worry about is bead diameter (assuming the frame has enough clearance for the tyre you want to fit). Inner tubes aren't particularly critical provided they aren't too big to get inside the tyre before you inflate them. I've even used a 700c/27" tube in my ATB (26") wheel to get me home.

Not sure what the 15c means but it's likely to be the width of the rim (15mm?) as you suggested.