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

Quote Originally Posted by Tezzwokka View Post
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.