tinyurl.com/yeaxk2e
You live and learn.
Last edited by: VxFan on Tue 28 Aug 12 at 10:35
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Something else I didn't know, although it may have been discussed here before:
"from 1st November 2012, every new car sold in Europe will have a TPMS [tyre pressure monitoring system] fitted as standard."
EDIT: www.car4play.com/forum/post/index.htm?t=7871&v=f
and: www.car4play.com/forum/post/index.htm?t=8503&v=f
Last edited by: Focus on Tue 28 Aug 12 at 09:27
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>> Something else I didn't know, although it may have been discussed here before:
>>
>> "from 1st November 2012, every new car sold in Europe will have a TPMS [tyre
>> pressure monitoring system] fitted as standard."
>>
I don't think that's right - the 2012 date is for new type approvals. The production date is Nov 2014.
Once a car has ESP / ESC or whatever (which is mandatory now) then TPS can be done in software. It can be activated on my 2004 Mercedes by someone who knows what they're doing with the Mercedes diagnostic computer.
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>>
>> Once a car has ESP / ESC or whatever (which is mandatory now) then TPS
>> can be done in software. It can be activated on my 2004 Mercedes by someone
>> who knows what they're doing with the Mercedes diagnostic computer.
>>
Eh? There are interminable threads here and elsewhere on the subject of TPMS sensor failure. These things are transponders, usually fitted either as a type of valve cap or within the wheel.
How does a software mod install the sensors?
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AFAIK in most cars nowadays the tyre pressure sensors work by comparing the rate at which the wheels of a car rotate, the theory being I think that tyre with low pressure has a slightly smaller circumference and so rotates quicker. This is picked up by the ABS/ESP sensor, and so its presumably just a s/w update/mod to turn it into a visual or audible alert
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>> ............. the theory being I think that tyre with
>> low pressure has a slightly smaller circumference and so rotates quicker.
I would have thought that the decrease in the rolling radius would have more effect on the wheel speed than the decrease in the circumference.
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>> Eh? There are interminable threads here and elsewhere on the subject of TPMS sensor failure.
>> These things are transponders, usually fitted either as a type of valve cap or within
>> the wheel.
>> How does a software mod install the sensors?
>>
Probably why pressure sensors are so last year, dear. These days it is all done by the electronic spin doctors. :)
I really, really, miss all that carburettor tuning and points adjusting too. :(
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>> I don't think that's right - the 2012 date is for new type approvals. The
>> production date is Nov 2014.
>>
You may be right but Continental www.conticontact.co.uk/ say
"New legislation being enforced by the EU Parliament states that all new types of passenger vehicles (registered after 1st January 2012) must be installed with a tyre pressure monitoring system (TPMS) by 1st November 2012; furthermore all new vehicles will need to be fitted with TPMS by 1st November 2014. "
I don't know the distinction between "all new types of passenger vehicles" and "all new vehicles".
National www.national.co.uk/information/tyre-pressure.aspx say:
"Further to European Parliament laws, after November 1st 2012, TPMS will be installed as standard on all new cars sold within the European Union. "
Last edited by: John H on Tue 28 Aug 12 at 18:38
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>> Tyres lose pressure more quickly in warm weather....
What about if they're filled with nitrogen instead of air?
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As the link also explains that pressure varies with temperature, and you should always check pressure when the tyre is cold, that presumably means that the automatic devices either
a) correct for the effects of temperature, or
b) are not sensitive enough to notice.
So a hot tyre showing a normal pressure may actually be a leaking tyre ?
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>> As the link also explains that pressure varies with temperature, and you should always check
>> pressure when the tyre is cold, that presumably means that the automatic devices either
>> a) correct for the effects of temperature, or
>> b) are not sensitive enough to notice.
>>
>> So a hot tyre showing a normal pressure may actually be a leaking tyre ?
>>
Just don't park with your wheels in the sun in summer and you'll be ok...
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My car as standard came with a tyre pressure monitor. I upgraded it to the tyre pressure monitoring system when I ordered. So I see tyre pressures on the display. In cold weather pressures of course go down... quite a bit on the colder days last winter. It can also be set to monitor for full or partial load etc.
I'll see at tyre replacement time if the valves and transmitters still work!
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>> In cold weather pressures of course go down... quite a bit on the colder days
>> last winter.
>>
What do you mean by "quite a bit" (in percentage terms from your datum)?
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Should drop roughly 1% per 3C if Boyle's Law is right.
As opposed to Tucker's Law (v.sweary!) -
www.youtube.com/watch?v=xe3Ou9xBAlI
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Okay I exaggerated a bit. Percentage wise not by much I guess. Mine are meant to be say 2.5 bar and over the cold parts of the winter would be 2.3. But driven for a while at speed and it crept up to 2.5.
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People are confusing Tyre Pressure Monitoring with Flat Tyre Warning.
The former includes the functionality of the latter, but not vice-versa.
TPMS will show temperatures and pressures of tyres and warn of deviation, the system is based on battery powered transponders and antenna.
A flat tyre warning will show a flat tyre symbol and the fitted position, it is based on ABS wheel-speed signals being monitored, learned and compared.
Last edited by: sooty tailpipes on Thu 30 Aug 12 at 19:42
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Whenever I have had a flat tyre the car sags at one corner, pulls heavily to that side, and makes a noise like dragging a dead whale along the road.
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>> Whenever I have had a flat tyre the car sags at one corner, pulls heavily
>> to that side, and makes a noise like dragging a dead whale along the road.
i've seen motorists for whom even that isn't enough warning :)
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>> TPMS will show temperatures and pressures of tyres
No pressures only.
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You cannae change the laws o' physics, Jim. The hotter it gets, the more air diffuses out through the rubber.>>
>>
>> You live and learn.
>>
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and no doubt the sensors will be something else added to the growing list of MOT checks.
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I don't know if tyres lose pressure more quickly in high temperatures, but high road and ambient temperatures certainly raise tyre pressures in the short term.
I last checked the tyres three or four days ago in the middle of France, and set the pressures economically high then, but dodgily too because I was juggling an old-fashioned pen-type psi gauge and the French garage thing in atmospheres. Checked them again today and they were all quite low in the cool here. They really need doing every couple of days though, damn alloy wheels. And don't even mention the get-you-home skinny little spare, covered in filth and incapable of holding any air pressure. Piece of carp. I wonder how much five steel wheels would cost? Tyres aren't cheap in my size.
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those air pumps at petrol stations get dearer and dearer...i suppose they have to compete with inflation ..... il get my coat...shuffles toward door
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I think we are forgetting about volume here, unless you have a leak then the air within the tyre will remain constant regardless of temperature, surely as the tyre itself heats up it then becomes more compliant and the pressure exerted by the sidewall drops, as has been mentioned, Puncture detection uses the ABS sensors while TPS uses individual sensors on each wheel.
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>> surely as the tyre itself heats up it then becomes more compliant and the pressure exerted by the sidewall drops
As the air in the tyre heats up it exerts more pressure on the sidewall which in turn must exert the same pressure back.
The volume of the tyre will increase slightly as it warms up, but the effect does not fully offset the pressure increase due to heating.
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Err.. Surely the 'amount' of air in the tyre (volume) should stay the same regardless of temperature unless air is leaking by some method, as the air heats up its the pressure that increases causing the tyre to expand, does this mean we should have Summer & Winter tyre pressures set? :)
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>> Err.. Surely the 'amount' of air in the tyre (volume) should stay the same regardless
>> of temperature
But the volume does change with temperature (with constant pressure) - mass would be a better measure for 'amount'.
Last edited by: Focus on Sat 1 Sep 12 at 10:45
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>> But the volume does change
>>
I should imagine that for most tyres fitted to modern cars, the volume change is insignificant.
>> mass would be a better measure for 'amount'.
>>
except that air mass is leaking in a leaking tyre.
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I was just (pedantically) commenting on the use of volume to measure 'amount' of gas; not talking about tyres specifically.
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The tyre expands a little due to the increasing pressure but not by the same proportion as the pressure rises. All that steel reinforcement takes a lot of stretching!
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>> ......... unless you have a leak then the
>> air within the tyre will remain constant regardless of temperature, ..............
Perhaps the theory is that the inevitable permeation of air through the tyre carcase is greater when the temperature is higher.
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Tyres lose ppressure more quickly in warm weather - Focusless
