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Tyre pressures, A trap for the unwary

Discussion in 'New Riders and Riding Tips' started by Iffracem, Jan 30, 2005.

  1. Ok, so we all know that correct tyre pressures are verrrry verrrryy important, and we all check the pressures often, don't we?? (well, I do)

    But do we know how accurate the tyre guage is? hmmm?

    The story.....

    I pick up the bike after it's had the "pre-delivery" service I bludged out of the dealer, he assures me all is OK, I get on, and ride home... feels OK, But I've been off bikes for 20+ years, what do I know??.

    I do a couple of trips to work and back, and check the tyres (As part of a general "going over" it gets every week) and WHOOA, the tyres are about 5 psi down... Bugger! Pumps em up with the u-beaut air compressor I got in me shed, Sweeeet!

    I go for a ride, seems different, less stable. Must be the water on the road and cold temps.... I'll get used to it.
    Next day I have to do some heavy breaking around a steep downhill corner.. road is dry, I feel like I'm riding on a slug with polio! it's "squirming" all over the place, back worse that the front.
    By this time I've forgotten about the tyre check I did.

    Asked around, all sorts of theories are brought up, like my fat arse is too heavy for the little across (bloody cheek!), need to add pretension to the rear shock :? But why I thinks, there would have been stuff all load on the rear shock under heavy braking. Other Ideas are heavier shock oil, change riding position etc...... somebody mentions tyre pressure :idea:

    I gets home, pulls the trusty hand held tyre guage out of retirement and rechecks pressure...Hmmmm, both tyres about 8 psi OVER. I reset the tyres using the trusty guage, check using the compressors guage.. yep, it says 5 psi down... ride out to a mates place... bike feels great, his guage agrees with mine give or take 1/2 a psi

    Soooooo... moral of the story... get yerself a good tyre guage, look after it, dont trust sooper dooper compressor guages, or the service station guages. I've added a cable keeper clip to the Across's "boot" (to stop it bouncing around), my trusty guage now stays on the bike, and the slug with polio is gone!!

  2. Only set your tyre pressures when your tyres are cold.
    8 PSI over is about right after they have gotten up to temp.

    And yes, spend $50 on a decent tyre guage, the Michelin ones are awesome.
  3. Oh yes.. good point...
    By the time I found the guage the tyres were cold, everything was bloody cold!! :shock: , when I checked against the mates guage, we were testing the readings, not the actual pressure, which was higher due to operating temp.

    The ride is now good, and subsequent checks have shown the pressure to be okey dokey.

  4. Never, ever trust servo pump guages..... and air pressure and oil are the most under-rated most important aspects to safe, long lasting riding!
  5. Very true, I'm always surprised how often people rabbit on about different tyre, compounds, treads etc while giving little thought to tyre pressures.

    Jaycar are currently selling an excellent digital tyre pressure gauge (LCD display) which has a handy white LED light built in for just under $20.
  6. As long as it's accurate!

  7. Dunno about that marty, our local is sometimes up to 5-6psi out. Thats why i dont let my better half use it any more......
  8. i'm with "vic", the Michelin DIAL gauge is found in alot of race teams tool boxes.
    one of the most trusted gauges around , extremely accurate.
  9. Where can you get these from? I got a cheapie $7 gauge from Kmart. It does work, how accurate it is, who knows???

    Also, what's a good air compressor to get???

    :D :D
  10. I agree with Vic. Got one of these for about 45 bucks from Bike Mart and it is spot on.

  11. I use this you beaut digital readout tyre pumper-upper which has a large LCD display and you input the required tyre pressure. It then adjusts the pressure automatically. I don't know how accurate it is. But it's the only one that I can get onto the valve.

    Recently I read a comparo of tyre gauges. Might've been in AMCN. The review was largely useless as they didn't talk about the one important aspect of the gauges - accuracy. So, after reading it, I'm still no wiser as to what brand of hand gauge to get.
  12. How do you know? I mean, what are you calibrating it against, and how do you know that's accurate?
  13. Read an article about two years ago, by the RACV I think, regarding service station pressure gauges. They can be as much as 30% inaccurate. Therefore if inflating to 30psi (such as my cage), you may be anywhere between 20 and 40psi on a cold tyre!
  14. If they're a good design, they'll include specs like an error plus minus some value or percentage. And for $45, I'd like that error to be very low.
  15. I'd say as long as it is consistent, robust, and convenient to carry all the time, it's a useful guage. I think I paid about $8 for the metal slide guage I use.

    It satisfies all those requirements (and seems to be pretty accurate as well).
  16. My first Michelin hit the garage floor after it flipped out of my hand trying to not get caught by the stretched out spiral-hose, busted.
    2. one is now 8 years old. Friend worked at Draeger, a company making all sorts of measuring equipment (like the ignition cut-out/ alcohol-tester for cars, no starting until the thing tells you you're sober).
    He took the Michelin in for checking about 4 months ago.
    It was 0.125 psi out over the whole range against their test-equipment.
    Not bad for 8 years of abuse and vibration of 150.000km of touring (or more), living in the tooltray under the seat.
  17. And....? Shit yourself? :p :p
  18. looks like they have a new digi gauge :) wouldnt mind one

    Michelin Michelin Digital Tyre Gauge
    Digital gauge accurate to a +/- 1 PSI. Blue glow back lit display. Dual function display shows PSI and BAR.

    apparently solidly contructed dial gauges with a relief valve are the most accurate.
  19. I hope you took it back and asked for a refund!!! :LOL: