tyre pressure gauges

[Robtel]

Checked out the air pressures in the caravan tyres today in preparation for our first outing of the year next weekend. The recommended pressure is 55 psi. The initial reading with a hand helg gauge was 46 psi but when I connected up the 12v pump the reading on that was 55 psi. I checked the pressures with a further two gauges, one hand held ,one part of a pump and ended up with four entirely different readings. There were differences of up to 10psi, not just one or two.

Anyone else came across this? Anyone recommend an accurate make of gauge?

Thanks

Robert

 

[Tram]

Hi Rob,

I have a cheap pencil gauge, a

 

[rob_jax]

Rob,

Unless you know that the tyre pressure gauge was calibrated, or that it has a stated accuracy on the box, then it's quite common for these devices to be widely out.

And I'm afraid that Tram's surmise is wrong - the accuracy of a device and the display electronics are not connected. It costs nothing to include extra digits in a display and manufacturers add in the odd extra digit - in the hope that people will think it's better...

I design process control systems for refineries; understanding the precision and accuracy of measuring devices and the importance of matching that with the display - so that the users don't place unwarranted trust in a display with too many digits...

But a new digital pressure gauge has the best chance of being in calibration, so I'd go along with tram and suggest you buy a new gauge - and throw the old ones away.

Robert

 

[Sedo]

Hi Rob

I've used a pencil type gauge since 1971. Working at Michelin I had it checked twice against their calibrated gauges (which had to be set in France) and it was within 1 p.s.i. So I've used it ever since.

What's always staggered me is, there is no way of knowing if a gauge you buy, wether digital or mechanical, is accurate. Yet the different organisations involved keep banging on about safe tyre pressures.

On a test a few years ago the difference in readings at garage units was dire. Be interesting to know what the police check tyre pressures with?

All the best

Tomo

 

[Steve L]

Very interesting thread and some very valid points raised.

All of the guages you can get at your local accessory shops are realy only comarators and not calibrated to any degree.

I have a small 25Ltr home compressor which has a pressure regulator on it. I can set that to my tyre pressure required and I also have two inflators with their own guages built in.

I wonder how often our nation tyre depots calibrate their guages or if they don't bother.

It's worrying as 4psi difference on two tyres diagonally accross a car can produce very unstable cornering.

 

[Sedo]

Hi Steve

I use the pencil gauge mentioned above on my tyres, but also have a stirrup type pump for 'topping up'. The gauge on the stirrup pump differs usually by 4-5 psi with my gauge.

Also worth remembering if you have a tyre changed or repaired, the pressure in the tyre will be dependent not only on the accuracy of the gauge but also on the diligence of the person doing the work. I,ve checked tyres after having work done and they're way out. Another thing to remember is that the pressures will differ with the ambient temperatures. I know this can sound over the top but that air in your tyres can make an awful lot of difference on your safety and comfort.

All the best

Tomo

 

[rob_jax]

Tom and others,

Agree about variation in pressure readings between measuring devices - too right it's interesting, but for all the wrong reasons.

In my company's engineering R&D workshop we have instrumentation to measure pressures from almost a perfect vacuum, through the milliBar range, then upwards through pressures around atmospheric to tens, hundreds, and thousands of Bar...

And a few years back one of the guys made a rig to check tyre pressure gauges - and the differences were disturbing. 0.5 bar (about 7 psig) differences around 4 bar were not uncommon.

So I have a pencil gauge that was internally calibrated - and the waste bin got the ones that didn't work properly.

The dial gauge type (usually found on foot-pumps) are easy to read, but the cheap models have engineering problems that cause erratic readings...

I remember that trading standards are supposed to check garage forecourt tyre pressure systems - and they need to comply with an accuracy statement - I think it's 5% relative (but that's from memory)

Robert

 

[rob_jax]

In continuation,

Over on the Tyre Safe web-site - there is a campaign under-way to try an improve the situation with measuring tyre pressures:

"A staggering 60% of motorists were unable to check their tyre pressures due to airline equipment being out of order, which presents a concerning picture of the sub-standard condition of the services available to motorists at the nation's petrol forecourts"

"This echoes the worrying results revealed in a study by the automotive weekly publication, Auto Express, which found that 40% of airlines were faulty or inoperative"

Robert

 

[Lord Braykewynde]

Can anyone tell me of a decent 12v tyre pressure guage? I've had 3 different ones now, all from Argos and costing up to

 

[Carl-GreyhoundsrUs]

Can anyone tell me of a decent 12v tyre pressure guage? I've had 3 different ones now, all from Argos and costing up to

 

[cooky1]

The problem that I have is that my tyre pressures are 55psi, and my gauges only go up to 50psi!

What sort of small gauge does anyone use that will measure this pressure?

 

[JasonR_374341560]

For a wide range of Gauges try out

http://www.demon-tweeks.co.uk/products/search.asp?keyword=tyre pressure gauges&classCode=MSPORT&brandCode=all&x=24&y=8

 

[cooky1]

Thanks Jason, certainly a good price range on there.