[ChefClive]

Happy new year all. Right, the temp in hertfordshire England is -3 to 6 C at the moment and the car is showing a pressure loss in OSR - 27 instead of 37. I went around and checked and adjusted all the pressures and all was well. The next day we had to go over to Aylesbury, 50 mls. Starting up, the pressure warning came up again so I stopped off via our local tyre guys to check - all spot on and the warning went away. The technician said that the cold weather sometimes triggers these faults. Today, 7 C and Low pressure warning again even though the pressures are correct. Has anybody else witnessed this and what was the fix please? Thanks. Clive.

 

[dernotte]

I have noticed this a couple of times in cold weather. This happened yesterday, ambient temp was -15c, and all tires were reported as "low" in the dash. I visually check them : all good. I displayed the tires pressure in the dash to check them, and after 2 min, the alarm disappeared and pressure got back to normal.

 

[Maxwell_400]

I have noticed this a couple of times in cold weather. This happened yesterday, ambient temp was -15c, and all tires were reported as "low" in the dash. I visually check them : all good. I displayed the tires pressure in the dash to check them, and after 2 min, the alarm disappeared and pressure got back to normal.

pV=nRT

In Fahrenheit and psi:

How much does temperature affect tire pressure?

A good estimate is for every 10° fluctuation in air temperature, vehicle tire pressure will adjust by about 1 psi. So if outside air temperature decreases 30° from your last tire pressure adjustment, expect tire pressure to drop about 3 psi.

If temperatures get particularly arctic, the rate at which tires deflate can be greater than the 1 psi per 10° rule of thumb.

 

[dernotte]

Ahhh, good old pv = nrt formula. Yes I know it, that's why when I have this kind of notification, I wait a bit, wait for tires temp to go up a bit and see if pressure reajust by itself.
This is strange that I only see this "problem" this year, even if it is my third winter with the Jag.

 

[Maxwell_400]

Same set of tires, might be an aging effect ? I too got it this year when the temperature suddenly dropped from +5 to -15, maybe the gradient is part of the algorithm.

 

[dernotte]

We have -24c today, here in Montreal. I think I will saty warm inside the house today, no plan to check what the tire pressure is...