[VegasG42]

So I intentionally set all the tires a few PSI lower than the app and car requested when I got the car. Just mainly to improve the ride quality a bit.

No issues or low tire pressure warnings for the past 6 months.

Then last week, we had rain for the day, and when I got into the vehicle the next morning, I had the low pressure warning.

No biggie. I aired up all 4 tires and still had the warning.

Kind of odd since I aired everything up to 36 PSI, and the App and car was asking for 39 PSI.

Today when I was driving home from work, I see the car is requesting 42.9 PSI ........hmm ?

Is the car requesting different PSI values based on temperature, or is it just being wonky ?

[rautoiua]

Originally Posted by VegasG42

So I intentionally set all the tires a few PSI lower than the app and car requested when I got the car. Just mainly to improve the ride quality a bit.

No issues or low tire pressure warnings for the past 6 months.

Then last week, we had rain for the day, and when I got into the vehicle the next morning, I had the low pressure warning.

No biggie. I aired up all 4 tires and still had the warning.

Kind of odd since I aired everything up to 36 PSI, and the App and car was asking for 39 PSI.

Today when I was driving home from work, I see the car is requesting 42.9 PSI ........hmm ?

Is the car requesting different PSI values based on temperature, or is it just being wonky ?

This is normal. Because when outside is cold, the air takes up less volume. You can have this kind of messages when outside is very hot and suddenly is raining and also the outside temp goes down as the 'ideal' pressure in the tires will be lower.

As an example at how much the temperature(this time the air inside the tire and the wheel itself) will affect how the car will perform:

When I m going racing I have a hatchback with 195/50/15 wheels(I know...tiny compared to our cars) and I start when cold with 1.5bar. After 2 laps of trying to heat them up it goes to 2.0-2.1 and that's the ideal pressure for those semislicks. If outside was very cold, I will be required to go 1.7bar or even more to go to that 2.0-2.1 bar target.

Keep in mind that the wheels will heat up from the grip of the tires with the road and most importantly from the heat of the brakes.

[Littlecoupe]

Another thing about the pressures I learned is the setting in your tire pressure app, if you're not constantly driving above 100MPH (like on the Autobahn), make sure your setting is set to <100MPH. This does not change the maximum speed limiter of the car (as far as I could tell...during a test), but it does reduce the request pressure values. I was getting ridiculous requested tire pressures of 45 PSI and higher during a cold snap in winter, so I changed the value to <100MPH and it went back to around 39 PSI.

[VegasG42]

Originally Posted by rautoiua

This is normal. Because when outside is cold, the air takes up less volume. You can have this kind of messages when outside is very hot and suddenly is raining and also the outside temp goes down as the 'ideal' pressure in the tires will be lower.

As an example at how much the temperature(this time the air inside the tire and the wheel itself) will affect how the car will perform:

When I m going racing I have a hatchback with 195/50/15 wheels(I know...tiny compared to our cars) and I start when cold with 1.5bar. After 2 laps of trying to heat them up it goes to 2.0-2.1 and that's the ideal pressure for those semislicks. If outside was very cold, I will be required to go 1.7bar or even more to go to that 2.0-2.1 bar target.

Keep in mind that the wheels will heat up from the grip of the tires with the road and most importantly from the heat of the brakes.

Very good information, thank you for that.

I was fairly certain that it was the extreme change of temperatures that caused the app and the car to adjust the required parameters of psi.

[VegasG42]

Originally Posted by Littlecoupe

Another thing about the pressures I learned is the setting in your tire pressure app, if you're not constantly driving above 100MPH (like on the Autobahn), make sure your setting is set to <100MPH. This does not change the maximum speed limiter of the car (as far as I could tell...during a test), but it does reduce the request pressure values. I was getting ridiculous requested tire pressures of 45 PSI and higher during a cold snap in winter, so I changed the value to <100MPH and it went back to around 39 PSI.

Yeah, I saw that adjustment when I was going through the settings in the car. I didn't want to mess with that though lol.

And now that you mentioned it, since it looks like the parameters are above or below 100 miles per hour, I might be guilty of exceeding the 100 mph parameter, so that possibly could cause the settings to adjust to ask for the higher PSI.

That makes sense