Tyre pressure guages

[Paul Wakefield]

I've got 3 tyre pressure guages. 2 of which are meant to be the bees knees and super accurate and one is cheap and nasty.

Trouble is they all give wildly different readings; I suspect the cheap and nasty is the most accurate!

The one I prefer to use because it is easy to get between the spokes and doesn't let out 2psi just by testing, undoubtedly significantly overreads (I think by 6psi) as the bike handles like a hippo afterwards. But it is well made and consistent in its readings so it is just a calibration issue.

Question: Who can I rely on to have an accurate guage so that I can recalibrate mine? Are dealers guages reliable? I presume the average garage forecourt ones are useless/dangerous and anyway they never give consistent readings.

Last week bike felt double jointed because pressures too low, now back end is all frisky so I've obviously got the rear too high despite using 2 guages and (poorly) educated guesswork.

All ideas gratefully received.

Paul

 

[littleredrooster]

But a new one!!

Halford's digital gauges did well in a recent RiDE test. Super-accurate and priced well.

 

[Paul Wakefield]

But a new one!!

Thanks for the thought but that's what I've already done which is why I'm more confused than ever!

The ones I have are meant to be super accurate (they are super consistent but that's not the same thing). Just because it performed well in a test does not mean the one I buy is going to be accurate - depends on quality control, luck, etc.

I've got to the stage I don't trust any guage unless I can test its calibration.

Paul

 

[wessie]

The gauges are probably not designed to operate in the current extreme temperatures.

Also, tyre pressures will wildly fluctuate in the current climate. Check them either late at night or early in the morning.

Personally, I find the pencil type gauge satisfactory. The one I use was given to my father at an agricultural show by Avon tyres over 30 years ago.

It works fine.

 

[pragmatix]

Personally, I find the pencil type gauge satisfactory. The one I use was given to my father at an agricultural show by Avon tyres over 30 years ago.

It works fine.

Most tests of tyre pressure gauges show that the most accurate is the pencil type, I use nothing else got one in the Discovery one on the gs and the missus has one in her freelander, all read within .5 Psi of each other the digital guage I got as a present is 4Psi out.

Pete A

 

[ozrockrat]

Repeatibility V Accuracy

Warning This is probably a boring ramble

Repeatibility is the ability of an instrument to read the same consisently (even if it is not accurate)

Accuracy is self explanatory but on nearly all instruments is only achieved a some point in the instruments range.

My suggestion is to find something to check the accuracy of the most repeatable one you have and take the readings to suit the pressures you will be checking.

When doing the calibration check make sure the pressure vessel has as large a capacity as possible to eliminate the possible bleeding off of pressure between readings.

My suggestion would be to find a tyre place that does heavy earth moving equipment and check yours against their liquid damped dial type gauges.

Also remember that temperature plays a big part in the pressure reading of a tyre. Always take your readings at a static known tyre pressure before riding (preferrably with a constant ambient temperature).

If you speak to a tyre distributer they may give you the formulas they use to calculate optium tyre pressures using temperature rise.

Sorry to prattle on but I used to be an instrument tech and then managed a mobile equipment fleet (and our tyres where up to $20,000 a pop) in my past lives (now I just travel the world and talk to people for a living)

 

[Paul Wakefield]

and our tyres where up to $20,000 a pop

T'would be a bloody big pop if one of those got a puncture!

Repeatability is what I have, accuracy is what I don't, something to check against is the challenge - thanks for the ideas on the latter.

Paul

 

[The Mechanic]

tyre pressures.....

Chuck all your digital whatsits and fangly gauges in the bin, get yourself a pencil gauge. Dunlop had a number on the market, some were able to read down as low as 2 p.s.i. these were ideal for Trials bike tyre settings but the good thing is everyone that I've tested (compared between different tyres on different machines,cars, etc) have always been within a nats cock of the real truth ie never more than 1 psi out.

Just as Pragmatix states they are reliable and the repeatability tets prove this.

Not to sure where you can get them now.

Most forecourt tyre pressure gauges had to be tested to confirm the accuracy, something to do with trade descriptions. Anyway some garages have a test gauge so you could try and do a comparison pressure test if the garage was willingto let you use it.

 

[MikeO]

Re: tyre pressures.....

Not to sure where you can get them now.

Got mine from Halfords last year - £3.99 IIRC

Mike

 

[adamski49]

Pencil gauge gets my vote too

Bloody hell - I was done... paid £4.99 at Halfords for mine

I agree pencil gauges are the most accurate and relaible.

I used to have and use regularly a dial gauge recommended in a bike mag test a good few years back until I had the misfortune to write off my GSX-R when the front let go instantly and without warning cranked over at a ton.

It was an early sunday morning in the summer, the road was relatively warm, bone dry, no spillages, mud or anything and the tyres were warm as I'd already covered about twenty miles. It was nearly a year (and still using the same bloody gauge) to figure out why the bike went down.

It kept nagging away as not only had I been faster round the same bend but I hadn't binned a bike in 18 years and wanted to know why - cue numerous advanced riding courses. In the end I dug out an old cheap gauge I had knocking around in the garage and compared pressures and lo and behold my supposedly accurate one was reading 4 - 5 psi under so over inflated tyres all round. Got a pencil one to double check and sure enough rogue gauge.

It was alright for years but I have a sneaking suspicion it may have been damaged through being dropped on more than one occasion - precision tools don't like being bounced.

Would I be correct in assuming pencil gauges remain accurate for a long time or do I need to buy a new one every few years? I don't want to get off at high speed again, it hurts and it costs too.

Adam

 

[Vern]

As long as you only use one all the time, and you know what it should say for your tyre pressures, It doesn't matter if it's accurate or not, as long as it's consistent, that's all that matters.

 

[AndyT]

Re: and our tyres where up to $20,000 a pop

T'would be a bloody big pop if one of those got a puncture!

Repeatability is what I have, accuracy is what I don't, something to check against is the challenge - thanks for the ideas on the latter.

Paul

If you wany to check it against something accurate you will probably have the perfect thing at home in the form of a hose pipe. Fill the pipe with water and suspend it from a bedroom window. The head of 27" of water is approx 1 psi. Now you can lift your hose pipe to a predefined point and have a calibrated gauge.

PS. Don't explain what you are doing to your neighbours and see if they look for one similar in B & Q.

Have Fun
AndyT

PS - I was also an Instrument tech long ago.........!!

 

[Paul Wakefield]

Now you can lift your hose pipe to a predefined point and have a calibrated gauge.

I'll give it a try at the weekend.

Paul

 

[The Mechanic]

Careful now laddies...

Should one be using tap water, spring water, hot water, ditch water........

The Pressure at a depth in a liquid, or in the air, equals the weight above a unit area. This gives the relation, pressure = depth x mean density x g.

So if you are above or below sea level there will be a difference, but how are you going to connect the guage under test to the hose pipe, and if the sun is out the hose will expand more quickly than the water and then the.........JUST GET A PENCIL GAUGE!

 

[Vern]

I'll get me coat

 

[PW Cymru]

Ride magazine were giving gauges away with annual subscription. The Snap-on bourdon tube type received read exactly the same as my Halfords foot pump.

You sure your using the right end. Only jokin