Low tyre pressure warning

[K1W1]

I thought this was better in another thread rather than the fuel consumption one.

One other thing, my tyre pressure warning came on not long after the rain started. A check found no reduced tyre pressure. Could it be the cooling of the tyres and slight reduction in pressure due to the wet road?

As far as I know the tyre pressure warning works by comparing the rotational speed of each wheel using the ABS sensors. The theory is that a tyre with reduced pressure will rotate at a different speed (presumably slower) than the other three. The warning will then come on.
So as far as I can see the change in ambient temperature or road conditions is unlikely to have caused the warning as all tyres would have cooled at the same speed and maintained a speed relative to each other.

[Calais]

My vRS has done the same thing, only once though.

It had just stopped raining and I was cruising at 100km/h. I pulled over to check my tyres for nails and stuff, found nothing then I checked the tyre pressures, reset TPS settings and havent had a problem since.

Seeing as the TPS works off the ABS sensors for determining individual wheel speed, I can see how a tiny amount of grit or water could foul the sensor, albeit momentarily.

[K1W1]

I can see how a tiny amount of grit or water could foul the sensor, albeit momentarily.

That makes sense to me.

[Tezzwokka]

Maybe it was due to a momentary fouling, as it hasn't happened again. Thanks for the input.

[pwcar]

Mine came on a few days after I got the car, was driving on a gravel road at the time, it has been on for about 3 weeks.
Nothing will get it to go off. Car is now at the dealers for investigation.
A deflated tyre would have a smaller diameter (and rolling radius), it would therefore spin faster for the same ground speed (that would be the diference that the ABS sensor could detect).

[Bayford Skoda]

Sometimes the TPS light will come on if the vehicle is unevenly loaded... i.e If you have heavy items on one side of the boot only as it reduces the rolling diameter of that wheel vs the other side.

[Maverick]

I thought this was better in another thread rather than the fuel consumption one.

As far as I know the tyre pressure warning works by comparing the rotational speed of each wheel using the ABS sensors. The theory is that a tyre with reduced pressure will rotate at a different speed (presumably slower) than the other three. The warning will then come on.
So as far as I can see the change in ambient temperature or road conditions is unlikely to have caused the warning as all tyres would have cooled at the same speed and maintained a speed relative to each other.

If anyone is interested in how it works in detail - Volkswagen Tyre Pressure Monitoring System (TPMS)

And a direct TPMS system to replace the indirect one - Fitting a direct Tyre Pressure Management System (TPMS)