[jadatis]

Originally Posted by mojoJJ

My car/app is kinda weird. They suggest different recommended pressures for tires at different times. No idea why. I have 21” staggered setup and right now the app recommends 42.1 PSI on both, front and rear.
I’ve verified that the tire size is set correctly, I’ve also reset the tire size and let the car auto detect tires (which it detects correctly), so not sure what’s going on.

Do you see the recomended pressure change during the trip.
If so its calculated up from a certain index-temperature, mostly 21 degr C/70 degr F.
That could be the reason why it gives 42,1 psi

And most sensors send pressure in steps of 0,5 psi to the unit.
Once receved by the unit, its yust a matter of software how its presented to you.
Some motorcycle tmps give pressure calculated back to an index-temperature, using the temperature of gascompound send trough by the sensors.

[I2P]

Originally Posted by jad03060

Just driving the vehicle will raise the pressures and the faster you go, since they will flex more, the pressure will go even higher. It can take a while for them to cool off after driving, too, especially if you're parked on hot asphalt or the sun is shining on one side...that side will have a higher pressure than the other.

If you follow the recommendation in the app, as long as you don't wait too long after stopping again since it only updates while driving, you should be good. The recommended pressure represents cold tires at typical room temperature, which is a rare occurrence, so the app's recommendation is likely much more accurate IF you've got the right tires selected in iDrive.

If you have a TPMS test tool, you can sample the TPMS data any time...pressure will go up about 1#/10 degrees F (based on a nominal 70F), so you should be able to map that against the door chart to get the best current recommendation. That test tool will also tell you the battery level. I picked one up on a super one-day sale as I had two vehicles each with two sets of tires, so it made sense to be able to monitor things as the aged. The battery in a TPMS doesn't last forever, so it's not a bad idea to check it prior to changing tires in case they're getting low...change them at the same time to save costs required to dismount later and rebalance after replacement of the sensor.

What model of TPMS Test Tool do you have/recommend?

[jad03060]

I bought one on a whim where it was on a one-day sale at less than 50% of the regular price...so, only have experience with one...it's made by Autel, but there are lots of them out there. I wouldn't have bought it if it wasn't relatively cheap, about $75...don't remember exactly, it was years ago.

[I2P]

Originally Posted by jad03060

I bought one on a whim where it was on a one-day sale at less than 50% of the regular price...so, only have experience with one...it's made by Autel, but there are lots of them out there. I wouldn't have bought it if it wasn't relatively cheap, about $75...don't remember exactly, it was years ago.

What is the Autel model number?