Last friday night on long run up north I felt the car was handling very strangely, wallowing around corners and over bumps, and lacking the usual precise steering directness.

I checked the tyre pressures the next day, and they were way down as far as 30 psi, which presumably had caused the problem.

I had set the pressures correctly at 32 psi the day before going down to Lancashire the previous week. (I can't have slow punctures on every tyre.)

When I set the tyres at 32 it must have been very hot during the day (as it was in Lancashire), but much cooler in the highlands in the evening.

Could temperature variations such as these cause as much as 1 to 2 psi difference in the tyre pressures ?

 

When checking the tyre pressures on a relatives car before a long journey, one half of the car was in direct sunlight and it put the pressures up by 3 psi on the affected side

 

Or more accurately.... (isn't the Internet amazing)
an increase of 5.555 degrees centigrade (10 Farenheit) will result in an increase in pressure of 1 psi.

I would think you could have easily got a change of 11 degrees Euan.

 

RTFM well ok you don't have to. I checked 'cause I had similar concern recently.

The manual says that when hot, the pressures could run up to 4-5psi higher than cold. The 32 psi setting is for cold tyres and with a bit of running around and the hot weather, 32 at hot would equate to some soggy handling I guess. I topped mine up to 34psi from 32 whilst hot and the handling tidied up a bit.

Waiting for a chance to re-check in some cooler weather.