Silly Road tyre pressures?

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  • Silly Road tyre pressures?
  • crikey
    Member

    The larger the tyre the lower pressure needed; think about car tyres at 30 psi.

    Quite a few road tyres will take 145 psi, and a few people will pump them that high in the mistaken knowledge that harder tyres = faster. Usually those who do time trials…

    Higher pressures are used on the track too.

    deviant
    Member

    I stick to 100 psi in a nice soft folding tyre, a happy compromise between fast rolling and comfort, when i tried 120 psi i felt every little bump in the road and the ride was distinctly unpleasant.

    Premier Icon crazy-legs
    Subscriber

    I don’t even use that pressure on the track!
    Road = approx 100psi. 110 or so for nice smooth roads, 90-100 if it’s wet or the road surface is rubbish.
    Track = 120psi.

    Harder tyres just give you a harsher ride, there’s almost no speed gain from having them at 140 instead of 110.

    trail_rat
    Member

    Lol at crikey

    So tts are never on smooth roads ? Ad i mean never.

    Agree no meed for silly high on road riding where surfaces are mixed but general experiance in tting is courses are on smooth roads or are not popular as they become slow courses.

    There is/was a scale on the continental site of recomended pressures against rider weight. IIRC I was about 105psi at 90kg on 23mm tyres.

    I’d not go much higher as the tyre may well take it, but will the rim?

    Track tubs go upto something silly like 220psi.

    crikey
    Member

    TTs are often on smooth roads, but smooth in road terms is not the same as wooden track smooth. I’m speaking about an old acquaintance of mine who was first and foremost a tester, and the way his TT bike was set up was just daft, with the skinniest tubs he could find pumped up to mental pressures.

    I used his trispoke and rear disc in a prologue once, with clip on tri bars and went slower than I could have ridden on my race wheels and with drops; it was like riding on steel-shod wheels and every corner was dangerous.

    whatnobeer
    Member

    The pressures on the side walls are maximum pressures, not targets for your average joe to ride at!

    I used to ride my 23c road tyres at 95 psi ( weight about 60kg) and now that I run tubeless its down to about 80-85 psi.

    If you’re on the track then go mad, but otherwise all you’re doing is giving yourself a really uncomfortable ride.

    Premier Icon cookeaa
    Subscriber

    TBH having the full 8 bar in the 28mm on my commuter seems very good for commute is on a mix of smooth A roads and rough as you like lanes, I only went to that size to try and improve general comfort by having a larger volume, assuming my times would get slower ,but they’ve not.

    I don’t know if the silly high pressure negates that benefit but it does seem to roll well and is comfy, 9 bar on the other bike is probably overkill and I think I may drop it a bit before I go out for a ride later…

    I think what really surprised me was that an £8 tyre was rated to that pressure at all, I had equated low cost with weedy construction and hence lower pressure ratings… I was it seems quite wrong

    clubber
    Member

    As above, they’re maximum pressure, not recommended pressures.

    Typically (and IIRC) max pressure is usually around half of what they’ve tested them to actually blowing the tyre off the rim.

    trail_rat
    Member

    Zafiros are cheap as they hae a compound somewhere between hard plastic and a brick

    Premier Icon cookeaa
    Subscriber

    I was giving both my road bikes a once-over last night (commute in today / Ride out with a mate this evening) I came to top up the tyres on both and thought I’d actually have a look at the tyre wall labels for a change and double check the allowable pressures. The commuter has a 28mm Zaffiro which says “8 bar (120 psi)” seemed like a respectable value, especially for a larger tyre so I pumped it right up to the 8 bar limit…

    Then I came to do my Geared “proper” road bike which also has a pair of Zaffiro’ but in 23mm, the label on them states “10 bar (145psi)” Eh? These are pretty cheap tyres (under a tenner each) and I’ll admit to previously just putting in ~100psi and not really bothering to read any labels but 10 bar?!? That seems very high to me…

    So I only stuck 9 bar (130 psi) in just to see if they’d explode and kill me, they held on and I didn’t hear the tell tale gunshot sound from the Garage overnight so I assume they’re still intact… I’ll be interested to ride them later as I’ve never ridden on a tyre at that sort of pressure…

    Does anyone actually run ~10bar pressures normally?

    Are there that many tyres that can go to 10 bar (or higher)?

    I’m assuming the lower pressure rating for a wider tyre is simply due to the risk of them blowwing off the rim rather than the construction of the tyre itself…

    Premier Icon cookeaa
    Subscriber

    Yep the Zaffiro is Dirt cheap and F1 tyre soft and sticky it sure ain’t. I’m sure it’s not even on most peoples radar as appropriate for use as a “training tyre” but I’ve had just under 1000 miles flat free out of the 23mm pair already and the 28mm has clocked up ~400ish in the last few weeks both at 90 – 100psi, their durability seems good thus far, probably due to their compound choice…

    TBH I’m not that decerning or knowledgable when it comes to road tyres and their relative compounds but I’ve ridden far worse that the Zafirro.
    All I know is these have out-lasted the Shite Michelin they replaced and seem up to being on about Par with the Schwalbes I had before that, VFM / Fitness for purpose wise they get my vote for what it’s worth.

    Like I said I was simply unaware that 10 bar was even a feasible pressure (I figured maybe 8 bar Max), let alone one that such a cheap tyre could go to, I only wondered if anyone was actually using such pressures and indeed why, from your collective comments it sounds like Track and possibly TT use are the only acceptable time to do such things and the thread title was apt… I shall probably stick to the 6-7 bar range thank you for all helping to enlighten me…

    fubar
    Member

    This thread had me questioning my pressures so had to search and found some interesting / potentially useful links:

    atricle: http://www.bccclub.org/documents/Tireinflation.pdf

    and some calculators:

    http://www.dorkypantsr.us/bike-tire-pressure-calculator.html

    http://www.vittoria.com/tech/recom-tyre-pressure/

    I didn’t find the Contiental one

    Edric 64
    Member

    I put 150psi in my 19mm time trial tyres

    crikey
    Member

    I put 150psi in my 19mm time trial tyres

    You pointy helmeted wizard.

    Edric 64
    Member

    It doesnt make me any faster though !!!

    brakes
    Member

    the Zaffiro probably has a wire bead doesn’t it? that would explain the higher max. pressures.
    higher pressures in your tyres will make them more prone to getting cut.

    Mary Hinge
    Member

    Most rims aren’t rated above 120psi so I’m told.

    And when they get a bit worn due to braking high pressures could split the rim.

    !00 – 110 psi in my 23mm road tyres.

    cynic-al
    Member

    I like the 15% drop theory.

    @ 75kg I like 80/90psi in my 25mm tyres for road riding.

    monkeyfudger
    Member

    10 Bar for the win, about 61kg. Bike just feels better with the tyres rock hard. Seems fast enough.

    brakes
    Member

    that’s the thing, it feels faster when you’ve got more pressure in because you feel more of the road. like it feels faster when you take your sunglasses off because you can feel more of the wind. doesn’t mean that it is faster.

    cynic-al
    Member

    It;s like how rigid bikes feel faster, but clearly aren’t.

    monkeyfudger
    Member

    Placebo, feels fast so I pedal harder. Bet the gains are barely worth worrying about Vs what feels good to whoever is riding.

    Premier Icon benji
    Subscriber

    There was an interesting article cyclist magazine a few issues ago, that discussed tyres, and one of the interesting things was that above 110psi the tyre doesn’t really gain an extra benefits for rolling resistance just loses out heavily on ride quality and grip as the tyre can no longer deform, and therefore energy goes into lifting the whole bike rather than just deforming the tyre. Tend to run mine at 90 in the front and 100 in the rear, gives it nice balance, and feel.

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