NNervous_R

So I bought one recommended by Auto Express, but how do you know it's accurate? Only need one pressure to be spot on: 32 psi.

Any bright ideas how to check that it does read 32 psi at 32 psi?

(bet Adam Hart-Davis would work it out with some pieces of pipe & a lead weight)

you reds

Blind faith?

Failing that, you can 'aways' trust the airline gauges at Tesco

alex.stanley

I've got a digital one from Halfords which states on the packaging it is 95% accurate or so (can't quite remember now).

The forecourt pumps are usually waaay out - even the digital ones - so I always take my Halfords one with me and keep checking as I pump the tyres up: I tend to overinflate the tyre and then let the air back out until my gague is at the right pressure

mikerich

pressure test

If you bought one of the Autoexpress ones - don't the write-ups tell you what the margin of error is? Manufacturing inconsistencies apart?

NNervous_R

Yes, that's where I went to select one. I bought the Draper 69924 - which should be accurate. But I just want to double check!

mikerich

Yep, did the same thing when I got the S. Only Race-X was in the lead then.
I then found that the gauge on my footpump, the digi plastic one from Halfords and the Race-X showed really no practical difference in their readings. Certainly less than .5 a psi.
The first pothole you drive over, and they are difficult to avoid these days , is likely to destroy it all anyway

aldfort

None of the gauges you can buy commercially are "Certified". There is only one way to get a presure gauge accuratly tested and that is to have it calibrated against a "dead weight" system. This is vastly expensive to do for a tyre gauge and will cost more than the gauge is worth.

Most of the up-market ones you can buy are within 5% of stated reading across the range and usually much better then that in the mid range. However they are precision instruments and need looking after. Protect from dust, dirt and moisture and they should be good for several years and not drift out of spec.
If you paid a lot for the gauge it should tell you how good it was when it was made on the box.

Personally I've used those little chrome jobbies that look like a pen for years. They last about 3-5 years and are remarkably accurate until they get dirty.

eSeM

On a test I saw recently the Halfords

Dembo

I bought a foot pump from Halfords about a year ago, and that says 1psi accuracy on the box. All the electric ones said 2psi, which is why I bought the foot pump.

Of course you need to check them when cold. Drive to Tescos and it's already out.

UK Paul

Ah but there are others ways to check its accuracy.....

No need for a dead weight tester, comparison method with a calibrated pressure instrument is one way.

(I work in calibration).

+/-1 psi is as good as you will get in a reasonable price range, and even this would be dependant on atmos.pressure, temp, humidity etc, etc!