Accurate tyre pressure gauge?

[Scarletpimpofnel]

I measured someone's TP today and all tyres read much higher than they should be (tyres cold, no sun on them etc).

Tried another gauge and that roughly read correctly but wasn't consistently less than the previous one.

My two foot pump gauges are different again.

Now all of these are cheap gauges costing a few quid.

I don't want to pay a huge amount but what manufacturer's gauges can be trusted to be accurate? By accurate I'm thinking better than +/- 1 psi.

Thanks.

[Pica-Pica]

Unless you have proper calibration done, you can only compare two or three gauges. I bought a TireTek analogue gauge, thinking it would be more accurate than my Halfords digital gauge, but they both read the same.

In the end, even if they were 1 or 2 psi out from the true pressure, I make an initial setting and then adjust according to how the car rides and feels.

I find my TPMS seems only to match the initial cold setting, when warmed up. Whether that is designed in element or not, I don’t know. As said, I go by the ride and feel.

Edited by Pica-Pica on Sunday 13th November 23:17

[tapkaJohnD]

The "Correct" tyre pressure promoted by the manufacturers is very much one derived from estimates and measurement of all the parameters that a tyre should have, performance, wear, comfort. It's an average for the average driver/driving style/car/road surface. And, as the OP says, temperature changes the pressure, as does the load in the vehicle. All these can make a single measurement vary in use by 5% or more, so that much variance in your gauge is immaterial.
John

[QJumper]

As PIca-Pica says, you can only really compare gauges without proper calibration, so have to take it a bit on faith. I just use mine to enure that all tyres are the same.

[Scarletpimpofnel]

Thanks all.

I appreciate in reality tyre pressure isn't a precise art so no need to be too accurate, but my ocd kicked in with the wide range of readings I got from my existing gauges and had to get something I could trust.

Ended up buying a Michelin product, as I trust that brand and like their tyres.

This one ...

https://www.ebay.co.uk/itm/295281267339?epid=11017...

[Dogwatch]

Probably more important to avoid filling station tyre guages if possible and check all tyres with the same guage.

The old "pencil" style pressure guages were always reckoned to be pretty accurate too.

[Zarco]

I've had a couple of Michelin digital ones for 15yrs. Does the job for me. Guess they are a previous version of that linked above.

My top tip is don't keep it in your pocket. The little torch gets turned on and drains the battery.

[trickywoo]

I’ve had a Draper branded digital one for a few years. Easy to use and I’ve verified it with a high end analogue one as well as tested against other digital options. Most are pretty good to be fair.

A colleague had a Michelin branded digital inflator with stopped pumping at a preset pressure. I was dubious but it was bang on.

[E-bmw]

If you want a gauge you can trust and want it to be accurate get a digital one.

I have worked for over 30 years with pressure measuring instruments of all kinds & would have no other, even a cheap digital will hold a level of accuracy only dreamed of with analogue gauges.

When I used to have to pressure test with analogue gauges we had to calibrate them before every use & that is ones that are only transported to use carefully in padded flight cases, and cost well over £1000 each.

When kept in a tool box the accuracy will be useless within a few uses.

[BFleming]

trickywoo said:

A colleague had a Michelin branded digital inflator with stopped pumping at a preset pressure. I was dubious but it was bang on.

I have this one as well. I have a compressor with an analogue tyre gauge, and the 2 read exactly the same. I can't remember where I bought it (prob Halfords) but it looks like this one:

[Paul_M3]

E-bmw said:

If you want a gauge you can trust and want it to be accurate get a digital one.

I have worked for over 30 years with pressure measuring instruments of all kinds & would have no other, even a cheap digital will hold a level of accuracy only dreamed of with analogue gauges.

When I used to have to pressure test with analogue gauges we had to calibrate them before every use & that is ones that are only transported to use carefully in padded flight cases, and cost well over £1000 each.

When kept in a tool box the accuracy will be useless within a few uses.

I'm sorry, but this is simply wrong.

A decent analogue gauge may well be far more accurate than a cheap digital one.

And as for being useless after a few uses....

I've got this Blue-point one which is a Snap-On subdivision.

https://www.cycleworld.com/resizer/y4l3mto7uKK4Tr1...

It's 12 years old, has come to loads of track days with me, and lives in a tool bag. It is still 100% accurate, which almost certainly cannot be said for some of the cheaper digital ones.

[Krikkit]

Paul_M3 said:

E-bmw said:

If you want a gauge you can trust and want it to be accurate get a digital one.

I have worked for over 30 years with pressure measuring instruments of all kinds & would have no other, even a cheap digital will hold a level of accuracy only dreamed of with analogue gauges.

When I used to have to pressure test with analogue gauges we had to calibrate them before every use & that is ones that are only transported to use carefully in padded flight cases, and cost well over £1000 each.

When kept in a tool box the accuracy will be useless within a few uses.

I'm sorry, but this is simply wrong.

A decent analogue gauge may well be far more accurate than a cheap digital one.

And as for being useless after a few uses....

I've got this Blue-point one which is a Snap-On subdivision.

https://www.cycleworld.com/resizer/y4l3mto7uKK4Tr1...

It's 12 years old, has come to loads of track days with me, and lives in a tool bag. It is still 100% accurate, which almost certainly cannot be said for some of the cheaper digital ones.

If you've only ever had one gauge, with nothing else to calibrate it against, how can you know it hasn't wandered in accuracy over the years? One thing that can be said with certainty is, it's not 100% accurate, that's completely impossible.

A brief run-down on analogue vs digital from a much better source than me: https://www.ralstoninst.com/applications/14-reason...

[Paul_M3]

Krikkit said:

If you've only ever had one gauge, with nothing else to calibrate it against, how can you know it hasn't wandered in accuracy over the years? One thing that can be said with certainty is, it's not 100% accurate, that's completely impossible.

A brief run-down on analogue vs digital from a much better source than me: https://www.ralstoninst.com/applications/14-reason...

I'm a control and instrumentation engineer at Sizewell B Nuclear Power Station.

I did a calibration check of it using the £30,000 Additel 761 we use to calibrate the plant instruments. (One of these if you're interested: https://www.additel.com/product-detail.html/761A-d...

It was 100% accurate when taken in context of the gauge resolution. i.e., at the cardinal points checked, the needle was dead centre of the gauge markings.

[Krikkit]

Paul_M3 said:

I'm a control and instrumentation engineer at Sizewell B Nuclear Power Station.

I did a calibration check of it using the £30,000 Additel 761 we use to calibrate the plant instruments. (One of these if you're interested: https://www.additel.com/product-detail.html/761A-d...

It was 100% accurate when taken in context of the gauge resolution. i.e., at the cardinal points checked, the needle was dead centre of the gauge markings.

Excellent, perhaps we should fetch the other instrumentation engineer in so you can argue it out?

[Paul_M3]

Krikkit said:

Excellent, perhaps we should fetch the other instrumentation engineer in so you can argue it out?

There's nothing to argue about.

If you're talking about analogue vs digital in proper industrial applications there's no contest. A digital instrument is far superior, far more accurate and will suffer far less drift.

But my comment was in response to 'analogue gauges will be useless after a couple of uses', and that a cheap £15 digital gauge will be accurate to levels that an analogue gauge can only dream of.

[Krikkit]

Paul_M3 said:

But my comment was in response to 'analogue gauges will be useless after a couple of uses', and that a cheap £15 digital gauge will be accurate to levels that an analogue gauge can only dream of.

FWIW I agree - would be interesting to test them in the same price ranges - £15, £30, £50 of analogue and digital and run them through their paces.

[Paul_M3]

Krikkit said:

Paul_M3 said:

But my comment was in response to 'analogue gauges will be useless after a couple of uses', and that a cheap £15 digital gauge will be accurate to levels that an analogue gauge can only dream of.

FWIW I agree - would be interesting to test them in the same price ranges - £15, £30, £50 of analogue and digital and run them through their paces.

Yeah, it would. I expect the results may be a bit random. Some digital gauges made for £5 in China may well happen to be more accurate than a £30 analogue gauge when tested, but I certainly wouldn't put money on it.

Even expensive electronic instruments can (and do) drift, that's why we have hundreds of routines to go check them at various intervals depending on their importance.

Magazines and the like sometimes do 'best tyre gauge' articles but they're not very good. They rarely publish the full suite of test results at various cardinal points, and often use something like a cars TPMS sensor as the reference (which may well be +/- 1psi itself)

That's understandable though, as it would be a lot more effort / expense for a magazine to access highly accurate calibrated equipment just to write a short article.

The only reason I check mine so thoroughly is because of all the track days and wanting accurate pressure measurements throughout the day, trying to keep them spot on as the tyres heat up.

For a daily driver, +/- 1 or 2 psi is more than good enough really.

[E-bmw]

Paul_M3 said:

Krikkit said:

Excellent, perhaps we should fetch the other instrumentation engineer in so you can argue it out?

There's nothing to argue about.

If you're talking about analogue vs digital in proper industrial applications there's no contest. A digital instrument is far superior, far more accurate and will suffer far less drift.

But my comment was in response to 'analogue gauges will be useless after a couple of uses', and that a cheap £15 digital gauge will be accurate to levels that an analogue gauge can only dream of.

I think you will find I actually said

E-bmw said:

When kept in a tool box the accuracy will be useless within a few uses.

I never used the words "accurate to levels that an analogue gauge can only dream of." and never meant that.

I simply stated that when an analogue gauge is rattling around in a tool box its accuracy will suffer whereas that of a digital gauge won't.

[bigshineybike]

Like Rolex self wind against any Casio, I suppose.
I came here because our Hyundai TPMS is being a nuisance and it's got me questioning my various tyre gauges.
I've got a few very old Dunlop stick type that are surprisingly close.
A proper workshop standard PCS MK2 on my airline and a Michelin branded Chinese thing that suffers so much hysteresis.

I shall try digital.

[E-bmw]

bigshineybike said:

Like Rolex self wind against any Casio, I suppose.
I came here because our Hyundai TPMS is being a nuisance and it's got me questioning my various tyre gauges.
I've got a few very old Dunlop stick type that are surprisingly close.
A proper workshop standard PCS MK2 on my airline and a Michelin branded Chinese thing that suffers so much hysteresis.

I shall try digital.

One thing to remember when setting tyre pressures is ALWAYS use the psi pressure to set the pressures rather than the bar pressure here is why.

Any digital pressure gauge will be 100% more consistent over any range of circumstances than any analogue gauge as analogue gauges use tiny little linkages & springs to transfer the pressure onto the gauge and these are affected by temperature, vibration, parallax errors and more, all of which will give inconsistencies into the readings.

Any digital gauge will likely read to one decimal place.

0.1 bar = 1.4504 psi

0.1 psi = 0.0069 bar

If you use psi the setting on the TPMS will be far more accurate & so generally any slight discrepancy in pressure due to temperature etc is far less likely to bring on an alarm.