I will fully admit that I'm nutty about gauges. Especially keeping a balence between the tires.
My Tire Pressure Monitoring System (TPM) is driving me wild.
I check all tires with both (I use two that read .5 pounds) my hand held gauges and get the same exact reading however the instrument cluster on the car shoots me something +,- 1 on different tires. I keep 34 in the front and 36 in the rear.
When cold, all four of the tires could have different reading, but as they warm they often sync up or vary briefly.
I ask as the readings were flawless/consistent coming from the factory, but since the dealer rotated and re-aired, they have been glitchy
How accurate are the factory TPM systems? Any way to get the tires to read the same all the time with out the constant messing?
Tires heat up and cool off as you are driving around, and not necessarily evenly based upon your driving. I'd just rely on your hand held guage reading, and trust that the TPMS will tell you if/when you get a flat. Mine has never failed to tell me when I flatted, once at 90 mph.
Since the TPMS only reads to a full PSI (no 0.x), the reading will be at best +/- 1 PSI.
Also from my experience, you can't always trust the tires to show in the correct position on the display. Since they auto learn the position, they don't always get it right.
The alternative is manual learning like my GMC which is a pain to reset every tire rotation.
My opinion is the TPMS has only one marginal benefit which is to alert you to a problem somewhere.
As stated by the others: The TPMS System is not designed to be that accurate. It is not designed to be a tire pressure gauge with an accuracy of 0.1 psi. There was no need to spend the money it would take to make it that accurate. A resolution of +/- 1 or even 2 psi does the job it is intended to do.
There was a "recall" or something my service guy told me about for the TPSM's. He ordered them for my car, but I didn't get them put in. I don't want my rims scratched or the tires not properly balanced so I will wait until I need new tires. My original ones work well enough for me; +/- a pound or two.
Maybe your TPMS sensors need replacing? Check with the dealer to see if your car is affected.
If you checked with your hand-held gauges and everything is equal when cold then leave it at that. No need to stress over the TPMS not being 100% accurate, if your OCD is that bad then change away from the TPMS display on the DID and stop thinking about it.
^^^^^^^^Best advice. However, if that doesn't work for your "reality," then have someone sit in the car and monitor the "air pressure gauge" while you fill each tire to the same pressure reading on the dash guage. That will correct for the "error tolerance" between the individual TPMS monitors - which is more then half a pound at 32 pounds:smile:
^^^ Then go through two left turns and the temperatures and pressures will be different again. They are accurate to within a pound or two which is all that matters.
My automotive OCD is a direct result of driving BMWs for years. Those cars were SO sensitive your steering wheel would be off center if your tires were 1 pound off. Accuracy became an obsession.