[Twempie]

Driving to work today and noticed that the TPMS warning light came on for one of the front tyres.  I've not checked thee air for ages and put some air into the tyre on the way home.  I will have a look tonight to see if I have picked up a nail.  Does anyone know what the the tolerance is for the TPMS?  The fronts should be set at 32 PSI.  how far below this does the pressure need to fall below this before it activates the system?
Cheers
Twempie

[Shambles]

Would be useful to know what pressure your tyre was at before you inflated it. Any idea?

One of mine has been down to 24psi and no warning. I use a digital gauge.

[Lorian]

Accordng to the systems spec the light will come on roughly at 25.6psi depending on the temperature.

The value does not increase if you decide to normally use a higher pressure than 32psi.

The pressure has to go back above 30.6psi to turn the light back off.

Whilst dirving the light will also illuminate if there is a sudden loss of pressure even if its still above the threshold.

[Twempie]

Thanks Lorian
Confession time - I've not checked the air pressure since 5,000 miles ago.  Do you think that it is likely that the pressure could have dropped from 32 to 25.6 PSI without there being a slow leak caused by a nail or something?  In other words is it reasonable to have lost this amount of air 'naturally' during this period (assuming that it was correctly inflated in the first place).  I drive about £18k a year and to be honest I seem to have got lazy since I bought the i30 as I'd always checked my pressures on my other cars reasonably regularly.
Cheers

[Lorian]

Best to check the pressure and take a look around the tyre. If I was betting man I'd be looking for an embedded foreign object.

[Twempie]

Have had a really good look at the tyre and can't see anything obvious (no sign of a nails or a tear etc).  I'll try and buy a digital pressure gauge tomorrow and monitor the pressure for a while to see if it remains stable.  I'll let you know how I can on.
Thanks again
Twempie

[Dazzler]

Hi Twempie,

I am a bit slack checking my tyre pressures (considering buying a A$300 TMPS accessory for my new car)

I cant ever recall (in 35 years / 26 different cars) having lost that much pressure in one tyre (naturally) e.g without some tyre damage or foreign body .. (could have a bit of dust in the valve I guess)

[Twempie]

Just gone online to order a decent pressure gauge and will start checking regularly.
Like yourself, I think it sounds like a slow puncture.  My son and I had a really good look a the tyre but nothing obvious is showing.
Cheers

[bumpkin]

Wouldn't bet on it being a slow, I tend to be pretty slack on checking the pressures also and every Autumn so far when the first frost arrives my dashboard is like a Christmas Tree, this would also be the same amount of loss as yours in the mileage you give, I only do about 6000 per annum.

[Surferdude]

Thanks Lorian
Confession time - I've not checked the air pressure since 5,000 miles ago.  Do you think that it is likely that the pressure could have dropped from 32 to 25.6 PSI without there being a slow leak caused by a nail or something?  In other words is it reasonable to have lost this amount of air 'naturally' during this period (assuming that it was correctly inflated in the first place).  I drive about £18k a year and to be honest I seem to have got lazy since I bought the i30 as I'd always checked my pressures on my other cars reasonably regularly.
Cheers

Based on your annual klms and the 5000 since you last checked, I estimating about 3-4 months. It's not uncommon for tyres to lose 5 or 6 psi in that time so it's likely that's all it is, but what were the pressures in your other tyres. One would ecpect they'd lose about the same.
Trev

[eye30]

I think it sounds like a slow puncture. 

Check that the tyre value is tight