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Tyre pressure gauges give different readings

Hi,

I used 2 different gauges, one gave about 43psi and the other about 31psi.
I tried the front tyre and also very different readings.

The spare tire though both gave the same.

One gauge is digital (https://auto.falcar.com/product.aspx?pid=1848103#.XZmapkYzbDc)
The other is a compressor with a gauge, not digital (https://auto.falcar.com/product.aspx?pid=1841578#.XZme5EYzbDc)

What’s going on?

Thanks

Of the 2, I’d trust the digital one over the one on the compressor.

I’ve never seen an accurate gauge on a cheap 12 volt compressor.

3 Likes

Gauges built in to compressors are often inaccurate, although this would be unusually far off. The one in my Ryobi inflator reads about 1 PSI too high fairly consistently, so I can use that in a pinch.

Do you have friends or family with gauges that you could use to get more measurements? If not, your mechanic would probably check the pressure for free.

Many of us here believe that the mechanical dial-type gauges are the most likely to be accurate.

The compressor gauges are almost always total BS… The Bourdon tube inside the gauge does not like the vibrations that it is exposed to on the compressor body.

In my experience the compressor gauge is a guess at best and almost always shows under psi… Just the way cheap compressor gauges do.

As @It_s_Me stated… I would trust the digital over compressor gauge as a matter of course and for certain.

I have a digital Accugauge and a 45 year old brass Meisner dial gauge. They both read the same to the pound and are within 1 pound of my cars dash readout. My compressor gauges are much less accurate. I use the compressor gauges only to tell when they are up to working pressure.

I believe some years back, Consumer Reports tested tire pressure gauges. It seems to me the dial gauges were more accurate than the pencil type, but it’s been so long ago that my memory may not be accurate.
I have a Black & Decker Air Station tire inflator. The gauge on that unit is inaccurate. It reads about 7 lbs high. I always check the inflation with my dial gauge.

ok I was a bit worries, I’ll trust the digital gauge!

Many thanks.