TPMS Setting

[Mdpresco]

While travelling on Saturday I noticed the TPMS widget displayed my left front tire was 5 PSI lower than the right front. It was at 35PSI. Today, I took the car to a shop. They found a nail in the tire at the edge at the edge the tread where it meets the sidewall. Cannot be patched or plugged reliably. So I will be replacing the tires on the front.

My questions are:
Is there any way to find the pressure setting for "low pressure" - when the TPMS would have alarmed?
If the tire shop swaps my rims when replacing my tires, will the TPMS system know this and display my pressures in the correct positions?

 

[Riley2323]

Those would be hardcoded in the car. The car just reads the output of the sensor and then uses the high and low pressure parameters coded into the car’s computer memory for the alerts.

What you’re suggesting is that every sensor has a SOC (system on a chip)…most sensors are just sensors to eliminate power requirements. The TPMS sensors have a built in 3V battery that lasts years. If they had SOC, the power requirements would probably need an 18650 type of power supply that would still probably just last months. SOC would be overkill for the TPMS and would increase their cost per unit significantly.

 

[enrique_7812x]

I don't know what number would trigger the warning, but at 35 psi, the pressure in the "bad" front tire looks to be in the "normal" range (33 psi or 38 psi depending on tire size) according to the 2023 G90 Owners Manual.

 

[Riley2323]

How long did you drive after they fixed the tire? Might need a start and stop cycle to clear the alert? Sometimes can take a couple miles or several minutes to get the correct reading.

If that doesn’t work take it up to 40 PSI and see if that gets it to go away and then let out the air until desired pressure.

Also read that if one sensor is below 25% of the others it will show too.

If you are in the Northeast, it is pretty damn cold so maybe warm garage to see if that clears it up.

 

[Mdpresco]

This is good to know.
OK. Our LS460 batteries lasted for 10 years. After rotating the tires you never knew which tire was low, only that one was low. Being a staggered setup, I now have a 50% chance of guessing which tire it is!
I was about 25 miles from home when I noticed the pressure at 35. Other pressures were 38-39. I did not get an alert.

 

[joegr]

...
If the tire shop swaps my rims when replacing my tires, will the TPMS system know this and display my pressures in the correct positions?

Yes, the car will figure out which sensor is which wheel with-in a mile or two of driving, even sooner if you make a lot of turns.