I took my car out for a drive after leaving it in the garage for 2 weeks and the psi light came on. I checked the psi on all four tires on the trip computer and at first it was 28 and after driving for a while it went up to 31 but the light was still on. From what i understand, anything below 28 is considered low but the strange thing is that my psi was 28 and it eventually went up to 31 but the light was still on. Does anyone have experienced this before? Is it because of the cold weather that makes it go crazy?

 

well, cold weather makes the tire pressure decrease but shouldn't mess with the displays and controls. Once it showed that one of my tires was missing air, so I came home, filled it up, parked it over night, and the next morning when I started driving the light was still. After about 5-10 minutes of driving everything went away and became normal. I guess it takes time for the computer to make sure that the tire pressure is A ok.

 

It is absolutely the cold weather. You have to adjust the pressure in your tires when it gets cold because the air in your tires is affected by temperature. High temps = higher tire pressure, Low temps = lower tire pressure.

The pressure in your tires (if they are the stock tires) is supposed to be at 35psi while cold. (after the car has been parked for at least 2 hours or so) So regardless of the season, the pressure should be 35psi. You will have to add air in the winter and take air out in the summer to maintain this pressure.

The low pressure warning comes on at 27psi plus or minus a pound or two. It is my understanding that the low pressure warning light should go off once you put the correct pressure in your tires and drive for a few miles.

 

I beleive the trigger is 32PSI to make it go off, have to drive for a few minutes, and tho this may be more thought then it does, but I think if you start the car and its immediatly 31 itll go off but if you start at 27 and go up to 31, it wont go off as quickly. I wonder if it can account for cold vs hot pressure.

 

I had the same thing happen the last 19 degree day we had here. The discusion at zchickz was that 35 pounds in winter, cold pressure was best. Of course get one of those warmer days and you'll be taking air out. Then putting back in. My feeling, drive careful till they warm. Those rims are worth it.

Most mornings now the tires are at 35. My "big" ride to work is 2miles or so. Yesterday morning the tires went up a half pound! One tire pressure read 34, the rest 35. By the time I got to work, the 34 was 35lbs, the 35's were still 35! It was 16 degrees! God I hate the winter!

 

It is the gas law in action. PV= nRT. when you drive the tires heat up, and the pressure increases. That is why it goes up. The sensors I have found are very accurate. YOu should have 35 psi COLD so I would fill them up regardless of how much they rise as you are driving. The change in pressure with temperature is especailly pronounced in low profile tires.

 

Another thing to watch out for during the winter is flat spots if you do not drive it regularly (like me). I added a few extra pounds to the cold psi. I'm at a bout 36-38 cold as of a couple days ago. I haven't driven it since Monday and probably will drive it once a week during the winter temps permitting (no snow tires). It has been in the teens in the evenings here lately so the RE040's are like ice skates. I'm near Boston so potholes and road debris are bad here anyway.