After my oil change, I checked the TPMS and it said 34 psi. And yes it is cold, as in, I didn't drive it at all. I changed my oil early in the morning (Cali weather woohoo). When I plugged in the tire pumper, the dial reads 32 psi. Is the TPMS off by a little or something? I also tested to see if the pumper has a bad dial, which is almost impossible cause I just bought it, by using one of those gauge that shoots out a bar and it also read 32 psi. After I pumped 2 more psi into the tires, the TPMS read 36 psi while the dial read 34. Explanations?

 

Not too sure. My car doesn't seem to have too big an issue but I never compared it side by side like that. More than likely it is a MOE between the system and sensors since they are done by calculations and when you use pressure guages on it they are more exact. This is just a guess though but I am pretty sure I read somewhere that other ppl have the same issue, looks to be something we all jus need to accept lol

 

it won't be an exact measurement, which is why you have a slight differential. i can't remember the exact explanation. something about the TPMS recording the pressure of the tire relative to the outside surroundings vs. if you take the actual pressure of the tire itself (like physical pressure vs. actual air pressure).

anyways, the TPMS readout just won't be the same as when you take a pressure gauge to your tire. close, but not the same.

 

TPMS seems to have about +2 psi vs. a physical pressure gauge. i just keep that in mind when i pump air in my tires. i usually go by my phyiscal pressure gauge...

 

Buy 5 of those common $2.00 push out gauges -- and if they are all within 2 lbs of each other, you did good. Take one apart and you will wonder why they are so accurate.

I have a digital gauge that I use to check the accuracy of the cheap, everyday, gauges that I keep in the car. The cheap ones seem to be rather consistent, but it is not unusual to see a 2-3 lb variation between several of them. And, I have seem some that were off even more -- but they are still much better than no gauge at all for those without TPMS.