Tire pressure question

[dakster]

My 25 Taycan 4s has 21” wheels. Dealer had 38psi on all 4 tires when I purchased it. Ride was amazing with 38psi.

I noticed the label on the door says 41 psi in front and 44 psi in the rear, so I added some air to match this on all tires. Now the app is saying I may have over inflated the tires. What am I missing? See attached photo.

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[BjörnfromHamburg]

I think if you run the tire-check in the PcM, that will dissapear.
Slightly lower pressure makes your tires glue to the road, bit fe inner wear on the front tires will be very likely.
And you can't see it.
I mostly go slightly over the recommended numbers.

 

[dakster]

I think if you run the tire-check in the PcM, that will dissapear.
Slightly lower pressure makes your tires glue to the road, bit fe inner wear on the front tires will be very likely.
And you can't see it.
I mostly go slightly over the recommended numbers.

I'll give this a try, but it looks like the car thinks all 4 tires should be at 38psi which contradicts with what's on the door.

 

[BjörnfromHamburg]

it adapts through the PCM and gives those figures if you change pressure.
At least I remember so.

 

[mikelevitt]

I'll give this a try, but it looks like the car thinks all 4 tires should be at 38psi which contradicts with what's on the door.

The car calibrates itself to where the pressures are when you reset it, regardless of what is recommended.

To rememdy this, fill the tires to the recommended pressures when cold. Then go into the settings and find the tire and wheel section. Set the tire and wheel size to a DIFFERENT size than what you actually have. Then set it back to the tire size you are actually running. Then drive the car. It will measure the pressures and this will be your new baseline. This allows owners to adjust the pressures to their liking but still maintain a warning if the pressure drops.

 

[WOOF]

Check that your tire size and type are correct in the PCM.

My car had 20" summer tires from the factory, so it was set correctly; my deviations make sense.

 

[mikelevitt]

It will not reset unless you select a different tire size and then reselect the original size. And you will continue to get warnings unless you do it.

 

[WOOF]

yes, I went thru that process though I don't remember what actually triggered it tbh...

 

[Murph7355]

One of the areas Porsche thought they could improve on 15yr old Audis and failed

 

[dakster]

PCM was set to partial load (40 psi front/rear). There is also a setting for full load (41 psi front, 44 psi rear). So the app is basing +/- based on this setting.

 

[M3Taycan]

PCM was set to partial load (40 psi front/rear). There is also a setting for full load (41 psi front, 44 psi rear). So the app is basing +/- based on this setting.

I made the pcm tire adjustment and it was corrected. Thanks!

 

[dakster]

I made the pcm tire adjustment and it was corrected. Thanks!

I am still little confused. If 41 and 44 psi are correctly rated pressure, why does the car say all 4 tires are +1? May be I am not understanding these numbers.

 

[M3Taycan]

I am still little confused. If 41 and 44 psi are correctly rated pressure, why does the car say all 4 tires are +1? May be I am not understanding these numbers.

When the TPMS was run the tires were at 40/43. During the drive they heat up, and +1 is the delta recorded.

 

[dakster]

According to the app, psi shown are the current measured psi and number in the parenthesis are the deviations. So according to the pic, 41/44 are current psi and the rated psi must be 40/43? Thus (+1)?
No big deal, just wanted to understand how this really works.

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