2010 460L owner. I've read a decent number of threads in here about where people keep their PSI (seems like 33 is the consensus). My computer has always shown 36-38 but my service dept always checks them and has documented during each oil change & tire rotation they have PSI at 33. I've never been bothered by it as I typically don't keep that displayed and always figured I'd rather it be a bit high than low. I was reading in the Car Chat forum about tire pressure gauges and ultimately bought one from Amazon (an AccuTire model) which showed 33 on 3 of my tires and 32.5 on the other. My computer shows 36 on all at cold start and up to 38 as I drive. I'm choosing to trust the device since my tires were just checked last week at a mechanic and read 33 and now I'm getting the same reading with my new gauge.

At least now I know the margin of error on the computer is somewhere around 3 PSI. If I ever see the computer display around 33 I'll do a manual check and assume I may have slightly low air. Anyone else have that big of a discrepancy?

 

I believe that if you study this more carefully, you will conclude that the pressures displayed in the dash accurately reflect the pressures in the tires.

 

 

 

 

Out of curiosity, why do you say that? The computer is the outlier by several PSI compared to what tire shops and my new device are getting. I would argue that gives me little/no confidence in the computer since various tire shops that check the pressure and now a digital gauge are coming out with the same readings...

 

Sometimes it's accurate but most of the time it's off 1 to 2 psi when I check it.

 

They are a good tool to keep a watch on the tire pressure. If you have swings on the display, best to have a tire pressure gauge in the car to check where you stand and react accordingly. I have put portable air pumps in all the cars to at least have a quick way to correct a low tire and then get to a tire shop...….

Never expected these systems to be "nuts on" given all of the variables....

 

I don't find much difference between my tire gauge and dash read out. The most important thing to me, however, is tire wear. I want it even.