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Losing air pressure in Tires?

Discussion in 'Bling and Appearance' started by DUK35, Mar 1, 2007.

  1. Hey guys - just a question, How often do your tires need pumping?

    I remember last time I pumped up my tires was around 6 weeks ago - and this week I checked - I lost 10 PSI in 6 weeks.....

    is this normal? do Bikes lose that much pressure in that amount of time or do bikes just need more attention to tires than cars?
  2. I'd say 10PSI in 6 weeks is NOT normal, bike tyres do need more atention than car tyres due to the reduced volume in them, mine tend to loose about 2psi in about 6-8 weeks
  3. depends on whether you have tubed or tubeless tyres to an extent. Are the tyres new but the tubes are old? They should be replaced as a pair.

    For tubeless tyres, older tyres are worse than new tyres - they get old and more porous (the material gets harder and little micro pores open up.

    The final problem is that cast alloy wheels are porous and many old rims are uncoated or have lost the coating that reduces air leaking through the wheel.

    Final problem is you may have a valve leak which is more easily fixed than a poor tyre or tube.
  4. hey - I think you might be correct - the tires appear to still be new- still has those rubber things sticking out around the tire.

    I have a feeling my Virago is tubed - I'll keep troubleshooting it....

    when you get dwon to 20psi - your bike gets soooo heavy it's annoying...
  5. i didn't mean new as in unworn but as in age (particularly if stored outside in the sun).

    It is not unusual for tyres to lose a couple of psi a week, and you may be exagerating it by not measuring pressure at equal states. Generally should cold (not been riding for quite some time and not kept in the sun). Changes in barometric pressure will influence your readings a bit and is not a problem with the tyre.
  6. A couple of psi a week is not that unusual. It's usually indicative of a poor valve. It's why you should check your tyres regularly.
  7. yeah it could be the tempurature aswell.

    I got this 6 dollar tire pressure gauge - measured it in the cold after 6 days of not riding it - reading was 20 psi -

    in terms of pumping it up - is it correct to say that I should take it for a little spin to warm the tires up then pump in 30psi of air?
  8. don't know the specifics of the bike, but 30 sounds light in general and very light for smaller tyres.
  9. no no no no no no no

    not only will riding around on flat tyres shorten their life, they cause handling problems. If you have to ride to a service station that isn't far away, fair enough, but don't try to warm up the air inside first.

    What manufacturers mean by "cold pressure" is the pressure the tyres are at when you haven't been using the tyre. The deflection of a tyre contributes a significant amount of heat to the air inside - you will find that after riding around for a while, the pressure in the tyre is higher than before you started - the manufacturer wants you to have, say, 35psi in the tyre when running - they calculate this backwards and get, say, 30psi 'cold'. That is the number that goes on the label.
  10. o'k' thanks - will get it to the nearest servo - just a 5 min ride away-

    I'll do 33psi then just to be on the average :)

    unless that's wrong again. lol