Changing tire pressure

What is causing my tire pressure to change in all 4 tires every day? I have noticed that in the last 2 weeks my tire pressure seems to be about 2 psi lower in 3 tires, with the fourth 4 psi. I took my car into sears and had them check the one tire with the lower 4 psi reading. They found no problems with the inside or outside of the tire. They put a black sealer on the rim and reseated the tire and inflated it again. I reset the low pressure light indicator in the car. My daughter used the car yesterday and said that the indicator light came on again. This morning I checked the tire pressure on 4 tires to find that 3 tires were 2 psi lower and the third was 3 psi lower. I filled the tires again to 30 psi and the indicator light went off. What is causing the lower tire pressure readings? I’ve never had any issues with my tire pressure before.

I can only think of two things - either your temperatures have been getting colder, or you have leak(s). If a high-quality tire gauge shows lower pressure each morning (before any driving), and the temps haven’t changed, the air’s getting out of the tire.

Are you parking in a garage overnight ??? I recently moved and now park in a garage. Last week when the weather (finally) turned cold, I had the exact same problem happen and never before did I have it. My “theory” is that parking inside a garage overnight (and filling the tires to the correct pressure) where the temperature is above freezing, and THEN driving and parking during the day in temperatures that are 20-25 degrees colder is creating this problem. That’s just a guess ???

You are right the temperatures have been colder. I think they say that you lose 1 psi per 10 degrees of temperature drop from when you filled the tires at a specific temperature. What I can’t understand is that I’ve never had this problem before. When sears checked the tire that I complained about, I watched an saw no air bubbles when they put the tire in the water tank and rotated it. I can see that the tires lost 2 psi when the temperature went down by 20 degrees, but if I filled it up today at the lower outside temperature with luck the pressure should be good when I check it later tonight or early tomorrow morning. I will get a new pressure
gauge today just in case the old one is no good. Thank again for your response. I will let you know how I make out. later P.S. the car always remains outside. The ladies use the garage. Happy Holidays to all.

Sounds like a good plan. Those digital gauges seem to work OK, just stay away from the ‘pencil’ style gauges.

Those pencil gauges are consistently inaccurate and that’s why I’ve always used them. If all four tires measure 17 lbs or 50 lbs, I know I’m good to go. But if one tire reads 12 lbs and the other three are at 20 lbs, I know I need some air. I get the accurate reading set up twice a year with changes for winter tires.

There was a recall on valve stems manufactured between July - Nov 2006. The rubber part of the stem may crack and cause a slow loss of tire pressure. Check the valve stems for any cracking and keep an eye on the tire that has a consistently lower pressure than the other three. Here is a link to a government site.

http://www-odi.nhtsa.dot.gov/recalls/results.cfm?rcl_id=08T018000&searchtype=quicksearch&summary=true&refurl=rss

Tires do lose about 1 PSI for each 10 degree top in temperature. Also I find after a short drive, tire pressure is about 3 psi higher than the cold pressure. I’ve seen a difference of 1 psi between the sunny and shaded side of my truck. The TPMS system on my wife’s 06 Sienna has to be reset after a tire rotation or installation. The procedure should be in the owners manual.

Ed B.

Does your Vehicle have a full size spare? My Highlander has one and it has a TPS in it. If the pressure drops in the spare the dash light will come on. If your spare is a doughnut type then it won’t have a TPS in it. Check the spare.

I had reset the tire (TPS) as per manual. My daughter said that after I put air in 2 of the tires this morning and reset the switch, 15 miles into her commute the light went off again. I’m going to recheck all the tires again 3 hours after my daughter gets home to see what the pressure readings are. I’ll let you know what I find out… Happy Hoildays to all.

No I keep it outside, but never had a problem like this. Happy Holidays. I will let you know if I resolve this issue.

Yes it has a full size spare, which I just had to use after 165,000 miles. I had no problems with the spare, only with the tires I replaced in October 2007. The problem only started in October of 2009, since that time I only had an issue with one tire, now it’s 3 tires that seem to always be low on air. I’ll let you know what I find out. Happy Holidays to all.

no it’s a full size spare. The problem only started in October of 2009. It was in only one tire, now it appears that it’s in 3 of the 4 replacement tires. It might just be the valve stems that edb1961 suggested. I will let you know what I find out. Happy Holiday to all.