Recently, the Tyre Pressure Warning on my Octavia Scout indicated a loss in the right hand rear tyre.

 

After some investigation, I found a screw head in the tread, so took the tyre to the local tyre fitters for repair.

 

After the repair, he asked what pressure I run the tyres at and I said 2.2 bar - so he put exactly 2.2 bar in (and let me see the gauge to confirm).

 

When I got home, I checked the pressure in that tyre and it was at 2.4 bar.  This has led me to question the accuracy of my tyre pressure gauge.  I use a Ring compressor with digital gauge and have the auto-shutoff set to 2.2 bar.  How accurate are these types of gauges?  Who's likely to be nearest the correct pressure, me or the tyre fitter?

 

I'm now thinking of getting a dedicated tyre pressure device - analogue, digital, what should I buy?

 

Once i've got the correct pressure, I can amend the settings on the compressor to suit - it is at least, consistent as I regularly check the pressures and normally they are pretty stable. 

How far was it from filling up the tyre to home?

 

 

When you drive your tyre heats up and the air inside expands, increasing the pressure.

 

This is why tyres should be checked when cold to get a level value as you don't know the temperature of your tyres.

How far was it from filling up the tyre to home?

 

It's about two miles of stop-start traffic, however I did wait about an hour and a half before checking the tyre pressures, so they ought to have been cold.

I have a ring compressor like yours and it is about 2 pounds per square inch higher in pressure to a very accurate hand gauge that I have if it helps at all.

Personally I've long used Schrader mechanical gauges. The simplicity of them means there's virtually nothing to go wrong & they're easily tucked in a pocket etc. If they do get damaged at least you can see it right away & don't get fooled by inaccurate readings.

OK so they don't have all the bells & whistles of the combined digital compressor-gauges, but for me that's a +.

WYSIWYG :yes:

Edited 18 August, 201510 yr by ProfesorDeBuceo

I bought this one as Auto express rated it and it accuracy...

http://www.halfords.com/motoring-travel/tools-diy/tyre-inflators-pressure-gauges/halfords-advanced-digital-tyre-pressure-gauge

Thanks for the comments so far - the problem is, how do I know it's accurate?  (Or how do I know how accurate it is?)

 

I assumed my Ring was pretty close to the mark, but I'm beginning to feel it's something in the region of 0.3 bar out - this equates to almost 5 psi!

 

I've spoken to some of the metering engineers at work and they're going to use a calibrated, traceable pressure source so I can at least quantify the Ring.

There is a BSI standard for pressure gauges, which pretty much all "pen type" gauges, even the Halfords' own brand ones, meet. The same cannot always be said of digital and "dial" gauges, or those on pumps, based on pretty much every test of pressure gauges I've ever seen.

 

So I'd suggest going to Halfords' and buying their "own brand" pressure and tread depth gauges for about £10 the pair. I literally don't leave home (by car) without mine.

I have the one linked above from Halfords and also the one just below it in the range and both read the same pressure when tested on the same tyre one after the other so I assume they are right. The advantage of the one linked above is you can calibrate it by pressing it to the valve but not firmly on. It also has an air bleed trigger which can come in handy. And to stop you having to check the recommended pressure n the fuel cap every time you can set a target pressure to. You have to click and collect if you want one though as they're in the back and not on the shelves

Thanks everyone.  Looks like a trip to Halfords is on the cards this weekend then!

I thought I'd better post an update here, just in case anyone is interested.

 

I managed to get a digital tyre pressure gauge (actually, I found two my wife had "stored" in a drawer - they just needed batteries!) and checked the pressures - one of the gauges only indicates in psi - tyre pressure reading 32 psi, the other had a setting for bar - 2.2 bar.

Interesting, and both agree with the Ring compressor gauge.  As far as I am concerned, this means the tyre fitters gauge is well out - and I had previously assumed their gauge would be the accurate one!

If you want accurate & virtually indestructible & with a bleed vale also there is only one...............

 

 

 

 

Newbow 4" dial with bleed valve............................I have one certified to 1% & calibrated with cert.........................

I've about 4 or 5 digital pressure gauges, not including the one on the compressor, and they all read different by +/- 3 PSI the only one to agree with my old pencil gauge was the one from either Lidil or Aldi that I bought several years ago.. my compressor reads 2 PSI over from anything over 30 to 36 PSI so once I've inflated the tyre it's checked with the digital gauge