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tyre pressures

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Community Veteran
Posts: 1,268
Thanks: 10
Registered: ‎30-07-2007

Re: tyre pressures

hmm actually i got that quite wrong [quote="wikipedia"]Indirect TPMS do not use physical pressure sensors. Indirect TPMS measure the "apparent" air pressure, by monitoring individual wheel rotational speeds, and other signals available outside the tire itself. Most indirect TPMS use the fact that an under-inflated tire has a slightly smaller diameter than a correctly inflated tire and therefore has to rotate at a higher angular velocity to cover the same distance as a correctly inflated tire. Newer developments of indirect TPMS can also detect simultaneous under-inflation in up to all four tires using vibration analysis of individual wheels or analysis of load shift effects during acceleration and/or cornering, which can be realized in software using advanced signal processing techniques. However, the vibration analysis technique requires the use of additional suspension sensors which result in increased complexity and cost of the overall system as long as vertical chassis movements are concerned. That is why most current advanced indirect systems use the spectral content of the wheel speed sensor signals so no additional sensors are needed and the computations can also be carried out by usual processors for example in usual ABS or ESC control units.
Indirect TPMS are realized in software in combination with wheel speed sensors for anti-lock braking systems, and electronic stability control systems. A disadvantage of indirect TPMS is that the driver must calibrate the system by pushing a reset button on the dashboard or through the on-board computer and if this is performed when any tire is in an under inflated condition then the system will not report correctly.
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Grafter
Posts: 1,867
Registered: ‎23-10-2008

Re: tyre pressures

Although it sounds more complicated that the old Renault offering, it does sound as if it has a chance of being less susceptible to malfunction. Thanks for sharing!
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Community Veteran
Posts: 1,268
Thanks: 10
Registered: ‎30-07-2007

Re: tyre pressures

my pleasure ... there's a load more on wikipedia about the direct-measure systems too which really is complicated!
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Community Veteran
Posts: 19,493
Thanks: 478
Registered: ‎12-08-2007

Re: tyre pressures

Just checked my tyre pressures and they were all 28 psi.  Guess this was done when I had the tyres fitted.  According to the handbook they should have been 31 psi so put a bit more air in them all Smiley Smiley
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Aspiring Hero
Posts: 12,475
Thanks: 598
Fixes: 19
Registered: ‎01-09-2007

Re: tyre pressures

Quote from: paulh
Quote from: Crucibleofevil
Provided the car is level, I don't touch them - they get re-pressurised at the next service anyway.

is that a leg-pull or do you really never check your tyre pressures between services?

I truly don't bother to check tyre pressure.

"In The Beginning Was The Word, And The Word Was Aardvark."

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Moderator
Moderator
Posts: 29,786
Thanks: 3,107
Fixes: 471
Registered: ‎14-04-2007

Re: tyre pressures

That's because he has solid rubber tyres Tongue

Customer and Forum Moderator. Windows 10 Firefox 80.0.1 (64-bit)

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Rising Star
Posts: 4,498
Thanks: 46
Registered: ‎13-04-2007

Re: tyre pressures

Quote from: Strat
That's because he has solid rubber tyres Tongue
Never gets any punctures  Wink
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Aspiring Hero
Posts: 12,475
Thanks: 598
Fixes: 19
Registered: ‎01-09-2007

Re: tyre pressures

Actually - I think that's almost true - I once had a very slow puncture - so I drove to the garage Cheesy
Otherwise not one; not ever.
That's over about 20 years.

"In The Beginning Was The Word, And The Word Was Aardvark."

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Grafter
Posts: 19,757
Registered: ‎30-07-2007

Re: tyre pressures

does it take long on you old bike?
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Grafter
Posts: 166
Registered: ‎21-01-2009

Re: tyre pressures

my normal method of checking tyre pressure is the old kick test - if they seem the same I go no further - so long as wear is even across the tyre
am not remotely bothered about the odd 0.1 BAR here or there -- have got a tyre pressure gauge somewhere
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Aspiring Hero
Posts: 12,475
Thanks: 598
Fixes: 19
Registered: ‎01-09-2007

Re: tyre pressures

I used to have tubular tyres on my bicycle - pressure about 120 psi - although the pressure gauge on my pump goes up to 140 psi.
(that's about 10 bar in new money).
If you could make any impression on the tyres, using manual methods, they were seriously under-pressurised.

"In The Beginning Was The Word, And The Word Was Aardvark."

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Community Veteran
Posts: 3,486
Registered: ‎02-10-2008

Re: tyre pressures

I've had a quick browse but not found what I want - so any experts here - Pierre-Pierre ?
How far off do tyres pressures have to be to start to have a significant effect on fuel consumption / tyre wear ?
And then of course if tyre pressures are out of balance between wheels - again how much of a pressure difference before significant inbalanc e in braking.
I was told that if they are badly out of balance then under hard braking there is a danger that the car would become unstable ? .
I'm sure in theory the professionals would say we should check tyre pressures every morning - certainly the military now have it on their daily check list, and I'm sure the police traffic police would say their cars have to have pressures checked every day - if not at the beginning of every shift ?.
Personally - I check mine every week, normally at the weekend - or before a long journey.
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Aspiring Hero
Posts: 12,475
Thanks: 598
Fixes: 19
Registered: ‎01-09-2007

Re: tyre pressures

Every time you check the pressure, a tiny quantity of air will escape... Cheesy

"In The Beginning Was The Word, And The Word Was Aardvark."

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Moderator
Moderator
Posts: 29,786
Thanks: 3,107
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Registered: ‎14-04-2007

Re: tyre pressures

If you buy tyres at Costco they will fill them with Nitrogen when they fit them.

Customer and Forum Moderator. Windows 10 Firefox 80.0.1 (64-bit)

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Community Veteran
Posts: 6,736
Thanks: 13
Registered: ‎02-02-2008

Re: tyre pressures

Quite clever really. The Oxygen market generates Nitrogen during manufacture, previously just vented, but now sold to tyre fitters.  Wink