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TPMS reading on the dash how accurate on Fiesta Mk8?

When I take a reading with my tyre meter I get around 36psi on the car showing 41psi.

Any thoughts?
 

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Both calibrated with different equipment.

Depends which you trust more for the accurate reading, then note what the other registers as and you can monitor the readings accordingly.

Personally, I'd trust a handheld tyre monitor more.
 

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Ditto. Inflate to the right pressure with a trusted pump from cold, 'store' on the dashboard setting then pay no attention to TPMS until one of the sensors goes off.

I've had two go off on the Focus now (when a 25%+ drop occurs from the stored setting) and that really is their one and only point, an early warning of a puncture.

Funnily enough I believe 41 is the reading they give to my correctly inflated front tyres too. The number is meaningless really, it's the relative drop they're measuring.
 

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Big difference between cold and warm tyres so make sure to compare like with like.

I would hope tpms was more accurate than a cheap Halfords gauge.
 

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And yet it isn't. It's just a tiny bit of gizmology sitting behind the valve.

A quality foot pump is much more robust and reliable and there's far less to go wrong on a simple calibrated pressure gauge.
 

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I do believe that the TPMS sensors are made for Ford by Schrader , if so they should be pretty damned accurate, id certainly expect them to be for the price of them new.
 

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You are welcome to put your faith in technology if you wish to... just know that you'll be running your tyres about 5psi under pressure compared to the a traditional mechanical measurement of air pressure 🤷🏻

I'll continue to trust a physical measurement to gain maximum performance, optimum fuel economy and maintain even tyre wear. Constantly running 5psi under is just wasting money.
 

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Only fly in that ointment is how do you know which device is giving the correct readings? Mechanical pressure gauges require frequent calibrations to stay accurate, electronic measurement may or may not be accurate depending on quality ,specification etc.


I personally have 4 pressure gauges, A makita 18v inflator with a 'high precision' digital read out , old style pencil pressure gauge, Michelin pressure digital gauge and a high quality Venhill mechanical gauge. None of which agree with each other with a variation of up to 2-3 PSI across them except for the pencil type gauge which is all over the shop so i tend not to use it but is around 30 years old to be fair lol.

So i tend to use them all as a guide and only one to balance my tyre pressures.

I only have a lowly MK 7.5 ST so ionly get a low-pressure warning with no fancy PSI read outs so thats one less thing i have to cross reference. Ignorance can be bliss after all.;)
 

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I always do my tyre pressures cold with a digital gauge that has Michelin embossed on it (no manufacturers name that l can see) and then set the TPMS which is always reading a few psi low and a difference on the left and right on both axles though set the same with the gauge.
As on observation if l check them after a run ie hot both the TPMS and gauge read the same and the TPMS evens itself out left to right.
On the subject of calibration you can only apply a calibration factor to most gauges ,wether mechanical or digital ,as there is no adjustment as such but to do this they would have to be checked over a range of pressures and of course the device it is being compared to would have to be a certified British Standard device which very few would have access to.
 

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How do you calibrate your pressure gauge?
I don't.

Its a Michelin so I trust it was made correctly. It has just one moving part with numbers marked on it that gets forced up by the pressure of air from the valve.

How can that possibly go wrong and work itself out of calibration?
 

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I don't.

Its a Michelin so I trust it was made correctly. It has just one moving part with numbers marked on it that gets forced up by the pressure of air from the valve.

How can that possibly go wrong and work itself out of calibration?
It’s a michelin but doesn’t guarantee it was made correctly, just like a lot of things in modern times it could be make the exact same way as another brand / generic brand but Michelin just pay to have their brand name stamped on it somewhere
 

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I don't.

Its a Michelin so I trust it was made correctly. It has just one moving part with numbers marked on it that gets forced up by the pressure of air from the valve.

How can that possibly go wrong and work itself out of calibration?
It’s called wear and tear .
It will have an internal valve with a seal that will wear over time and use.
 

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I don't.

Its a Michelin so I trust it was made correctly. It has just one moving part with numbers marked on it that gets forced up by the pressure of air from the valve.

How can that possibly go wrong and work itself out of calibration?
The mechanism could get sticky or something as simple as that and nothing lasts forever or is infallible.
 

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I'm pretty sure F1 teams or any professional motor racing team dont use a Halfords tyre pressure gauge or similar.
In fact they use super dooper highest of highest tech equipment, I Googled it.
 

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The mechanism could get sticky or something as simple as that and nothing lasts forever or is infallible.
But even if it were a 'potentially unreliable' item because it's one moving part somehow fails... its never let me down 🤷‍♂️

I've had it since I started driving and during that time I have never lost a single tyre to wear consistent with under or over inflation and i've achieved near legendary fuel economy figures while hypermiling. Until that starts happening it works and I trust it, that's all I can say 🤷🏻

And TPMS, on both cars, has consistently between 4-6psi out, EVERY time. But hey, as always each to their own, if you trust TPMS then use it for your tyre pressure readings. Its not me paying for any wasted fuel or more rapidly wearing tyres so its no skin off my nose.
 

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But even if it were a 'potentially unreliable' item because it's one moving part somehow fails... its never let me down 🤷‍♂️

I've had it since I started driving and during that time I have never lost a single tyre to wear consistent with under or over inflation and i've achieved near legendary fuel economy figures while hypermiling. Until that starts happening it works and I trust it, that's all I can say 🤷🏻

And TPMS, on both cars, has consistently between 4-6psi out, EVERY time. But hey, as always each to their own, if you trust TPMS then use it for your tyre pressure readings. Its not me paying for any wasted fuel or more rapidly wearing tyres so its no skin off my nose.
So self-righteous.🤷🤣
 

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I have to confess to considering the TPMS in any car only an approximate guide and there simply to give you advance warning of a significant loss of pressure. The use of a standard pressure guage is really the only method of setting the pressure to withing normal limits at ambient temperature, but of course these can differ slightly in their readings too.

The way I chose a guage was to read the reviews and select one that is calibrated to ANSI B40.1 Grade B (2%). They are not terribly expensive and at least when new, are meant to meet a certain standard of accuracy. Higher accuracy gets more and more expensive, but for normal road use, very high accuracy (F1 for example) is not really needed.
 
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