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28mm tyres

manic_essomanic_esso Posts: 92
edited June 2016 in Road general
Been reading about how these are the next best thing since, er well 25mm tyres. Apologies for the stupid question but how does one establish if there's enough clearance before actually buying said tyres. Surely it's not as simple as just measuring 28 mm from the rim...

The wheels are Fulcrum Racing 5 LG CX btw and obviously haven't got the tyres yet although Conti 4000s were the ones I was considering


  • keef66keef66 Posts: 13,123
    On a normal width rim a 28mm tyre will measure about 28mm wide and 28mm high; normally the tightest point is the width between the chainstays, but clearance beneath the fork crown and under brake calipers can also be an issue on some frames.

    So you can do a bit of measuring beforehand.

    You'll really need a few mm clearance because occasionally the tyre will pick up road debris and force it through the gap.

    I just had to revert to a 23mm tyre on the rear of my CR1 because the 25 was too close and there was scoring on the inside of the chainstays.

    ETA: just noticed your later comment re wheels. Those are wider rims, no? As I understand it, tyres will come up a bit bigger in both directions. What's the bike / frame??
  • VslowpaceVslowpace Posts: 189
    On my Fulcrum 5 LG 28mm 4000s won't fit in my bike, 25mm 4000s will, HTH. ;-)

    I don't think you'll ever truly know, unless it's blindingly obvious until you try it.

    Try friends or LBS before you buy. ?
  • mrb123mrb123 Posts: 3,974
    If you say what make/model of bike you have someone on here might have experience of fitting 28s on it.
  • manic_essomanic_esso Posts: 92
    It's a Wilier Izoard Ultegra

    2013 Model IIRC
  • bendertherobotbendertherobot Posts: 11,684
    How tight is the clearance on your existing 25c?
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  • Nick PayneNick Payne Posts: 288
    Pretty much impossible to give a prescriptive answer as some manufacturers 28s are identical in size to other manufacturers 25s.

    FWIW, I have some Conti GP 4 Seasons 28s that actually measure 26mm, and some Schwalbe Ultremo ZX 28s that actually measure 29mm.

    Tyres will also grow in size over the first couple of weeks of being inflated on a rim. My measurements were taken after the tyres had been in use for a few weeks.
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