Tyre Sizing

winoneday
winoneday Posts: 253
edited April 2008 in Workshop
The tyres that came on my new bike have 700x26c on the side of them. Having looked at alternative tyres on the internet most seem to be either 700x25 or 700x28. What exactly do these measurements mean and which would I be better off going for once my tyres need to be replaced?

Thanks.

Comments

  • Slow Downcp
    Slow Downcp Posts: 3,041
    It depends partly what riding you do, and partly what frame you have. Either will fit your rims, but the 28's may be too wide for your frame.

    I ride 23's on all my bikes (except MTB :wink: ), and they're fine for me, but the wider the tyre the more comfortable the ride.
    Carlsberg don't make cycle clothing, but if they did it would probably still not be as good as Assos
  • geoff_ss
    geoff_ss Posts: 1,201
    winoneday wrote:
    The tyres that came on my new bike have 700x26c on the side of them. Having looked at alternative tyres on the internet most seem to be either 700x25 or 700x28. What exactly do these measurements mean and which would I be better off going for once my tyres need to be replaced?

    Thanks.

    It all gets a bit confusing. Historically 700c tyres have a 622mm bead seating diameter (don't ask, but I could explain it - I think) For the record, 27" tyres, which used to be the standard, have a bead seating diameter of 630mm.

    The other number 25/23/28 etc is the depth (as opposed to the width) of the tyre in mm though the width will increase proportionately. So the overall diameter of a 700x25 tyre will be 622 + 2x25 = 672mm. In practice, manufacturers vary a little so it's not necessarily carved in stone.

    You'll probably find both 25 and 28mm tyres will fit your rim and clear the frame unless it's a very tight geometry.

    Geoff
    Old cyclists never die; they just fit smaller chainrings ... and pedal faster
  • musto_skiff
    musto_skiff Posts: 394
    AH go on - please explain why they are called 700C's
  • winoneday
    winoneday Posts: 253
    Thats great. The most important thing I was interested in was which would fit (obviously) but as its either theres no problems.

    Thanks guys.

    *Geoff - unlike musto I won't ask for the in depth explanation mainly as I doubt I would understand it no matter how clear you were.
  • John.T
    John.T Posts: 3,698
    When they were fist made they used bigger tyres and the overall diameter was 700mm. Read Sheldon Brown's article here.
    http://sheldonbrown.com/tyre-sizing.html
    Must type faster. You have got one anyway. The whole site is worth bookmarking. It would save a lot of threads on here.
    My Fleet.

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