Author Topic: Tyre pressure monitor  (Read 4287 times)

Offline Teutonic_Tamer

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Re: Tyre pressure monitor
« Reply #10 on: 25 February 2009, 16:12 »
Are the sensors paired with the axles? i.e if you change the wheels front to back or N/S to O/S they will not work?

Nope.  The TPMS works on a 'four channel' basis, whereby all four wheels are indvidually monitored.

However, if you happen to change the wheels around, then if the tyres have different rolling radiuses (either due to tyre wear, or simply due to different tyre brands/types), then the TPMS may very well send a warning.

I am sure when I had my tyres done a few months back the chap was speaking about this being the case?

Hmmmmmm . . . I doubt most tyre fitters would know the detail of how TPMS works - though they were correct in advising you of ramifications of rotating wheels around.
Sean - Independent Automotive Engineering Technician (ret'd)
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Offline stealthwolf

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Re: Tyre pressure monitor
« Reply #11 on: 25 February 2009, 19:14 »
Welcome back T_T.

Do NOT use any of the 'digital' pressure gauges - they are just far too unreliable.

Last weekend, inflated all tyres (after stealers seemed to have deflated them!) using a foot pump. Checked pressures using both an analogue guage like >this< and a digital guage like >this<. Both were congruent in their readings so I'm assuming this means that the digital one was adequately accurate compared to the analogue guage.

Offline pridders

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Re: Tyre pressure monitor
« Reply #12 on: 27 February 2009, 14:13 »


I am sure when I had my tyres done a few months back the chap was speaking about this being the case?

Hmmmmmm . . . I doubt most tyre fitters would know the detail of how TPMS works - though they were correct in advising you of ramifications of rotating wheels around.
[/quote]

Ohh dear I didnt realise this would be a problem! What are the ramifications?

Offline Teutonic_Tamer

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Re: Tyre pressure monitor
« Reply #13 on: 27 February 2009, 20:23 »
Welcome back T_T.

Do NOT use any of the 'digital' pressure gauges - they are just far too unreliable.

Last weekend, inflated all tyres (after stealers seemed to have deflated them!) using a foot pump. Checked pressures using both an analogue guage like >this< and a digital guage like >this<. Both were congruent in their readings so I'm assuming this means that the digital one was adequately accurate compared to the analogue guage.

You slightly missed my point.  The digital tyre pressure guages can be accurate, as you have found.  However, they have two problems - when the battery starts to go flat, the reading can then start to vary - and this error can be worsened by cooler temperatures (just like watch batteries - take the watch off your wrist, leave in a cold garage - and the LCD display will be very sluggish).  The other issue with digital ones is that they need to actually 'bleed' air out of the tyre to make a reading.

So, whilst they may be accurate, I would personally NOT recommend using them as your only source of checking tyre pressures - particualarly if you leave the digital gauge in a cold garage.

HTH
Sean - Independent Automotive Engineering Technician (ret'd)
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Offline Teutonic_Tamer

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Re: Tyre pressure monitor
« Reply #14 on: 27 February 2009, 20:27 »


I am sure when I had my tyres done a few months back the chap was speaking about this being the case?

Hmmmmmm . . . I doubt most tyre fitters would know the detail of how TPMS works - though they were correct in advising you of ramifications of rotating wheels around.

Ohh dear I didnt realise this would be a problem! What are the ramifications?[/quote]

If you swap part worn front tyres with virtually new rear tyres - then not only can the actual pressures be different, but more importantly for the Golf5 TPMS - the rolling radii will now have changed front to rear.  If you don't re-check your pressures, and press and hold the TPMS button - then the TPMS will not be as reliable compared to before the wheel rotation.

HTH
Sean - Independent Automotive Engineering Technician (ret'd)
-----
'06/7 Golf Mk5 GTI 5dr (BWA) DSG, colour coded,

I feel like a homo


Offline stealthwolf

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Re: Tyre pressure monitor
« Reply #15 on: 28 February 2009, 10:49 »
You slightly missed my point. The other issue with digital ones is that they need to actually 'bleed' air out of the tyre to make a reading.
So, whilst they may be accurate, I would personally NOT recommend using them as your only source of checking tyre pressures - particualarly if you leave the digital gauge in a cold garage.

Thanks TT. Didn't know they 'bled' air out to check the pressure. Both guages are kept in the boot of the car, so it shouldn't be freezing cold, I hope!