Tire pressure after buying

[tchavei]

Let's just agree it's a bit weird

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[RAHRCR]

So, safe to say that the dealer put in too much air and I should let some out, or do they know something that the app/car doesn’t?

21” Mission E wheels.

41/44 is my cold pressure target based on the sticker on the car. ?

 

[whitex]

My car has been in my garage since yesterday. Even though the tire pressures are supposedly measures only when driving, apparently the car reported a measurement 50 minutes ago. Given it's about 63F outside, garage probably similar temp, I'm going to guess "cold tire" is probably defined at maybe 50F/10C? I currently have R20 all-seasons on at partial load, PCM says it's expecting 35's all around, which agrees with the pressure differential of +1psi showing:

 

[magnitude]

The current pressures are actual, not adjusted for temperatures, so the tires which are at exact desired pressures can show different values as their temps may differ. The pressure deviation is adjusted for temperature (according to the manual).

Ah, that makes perfect sense.

What makes a little bit less sense, is that the deviation is now showing 6 and 7 psi respectively for my rear tires.

Since this is temperature-compensated, it should have stayed stable. I didn't mess with the tires, and I doubt someone's put air in without my knowledge... ?

I guess my best option is to let them cool down and then carefully drive to an air station, and measure there. (The "careful" part only so that they don't heat up messing with my measurements, not because I think they're about to blow, they should be well within tolerances.)

 

[wurzitup]

The door placard is for full load, and is waaaaayy to high for my 21 Mission Es. And the car rides like shit when it's up at these cold pressures. I've been using the partial load, 21" summer tire pressures which from my recollection are 34 front 36 rear and make for a much more comfortable ride. Tires have worn very evenly, and I am about to replace all four with Michelins. Got 31,000 out of fronts, and about half that out of each of 2 pairs of rear Pirelllis.
Tires are always inflated and adjusted first thing in the morning cold at 60-70 degrees.

 

[magnitude]

which from my recollection are 34 front 36 rear and make for a much more comfortable ride.

Makes sense, but I didn't even mind the much less comfortable ride in the Boxster. What I do mind, however, is noise, and usually more pressure makes less noise. So I'll try keep them at the upper end of the recommendation (which might be what they currently have, don't know yet).

 

[whitex]

Ah, that makes perfect sense.

What makes a little bit less sense, is that the deviation is now showing 6 and 7 psi respectively for my rear tires.

Since this is temperature-compensated, it should have stayed stable. I didn't mess with the tires, and I doubt someone's put air in without my knowledge... ?

I guess my best option is to let them cool down and then carefully drive to an air station, and measure there. (The "careful" part only so that they don't heat up messing with my measurements, not because I think they're about to blow, they should be well within tolerances.)

I would just cool them off, then go fill up to recommended pressures when it's 10C or less outside. If it's hotter, add a couple of PSI. After you drive home, check out the differential pressure, they should all be positive. Then when the car cools off, let the recommended differential pressure out of each tire - ignore the actual/absolute pressure, just let out however much the car says it wants (no compressor needed, just a gauge you can pick up for a $5). After I did that, I got it to show 0 differential. Weather got warm recently and all my tires are showing +1psi now, I suspect I was on the verge, was +0.44 before and now +0.45 which got rounded to 0 and now to 1, or something like that. It was cold when I did that, ended up dropping my tires to 34psi to get the car to show 0 differential (with 35 expected).

 

[whitex]

The door placard is for full load, and is waaaaayy to high for my 21 Mission Es. And the car rides like shit when it's up at these cold pressures. I've been using the partial load, 21" summer tire pressures which from my recollection are 34 front 36 rear and make for a much more comfortable ride. Tires have worn very evenly, and I am about to replace all four with Michelins. Got 31,000 out of fronts, and about half that out of each of 2 pairs of rear Pirelllis.
Tires are always inflated and adjusted first thing in the morning cold at 60-70 degrees.

Check you PCM for recommended pressures for full load or partial load. The door sticker is old tech and probably outdated by the time it's put on the car. Use partial load if you want lower pressures (unless you have your Taycan loaded with 400kg of crap).

 

[tchavei]

Well, I'm now suffering from the same deviations.

I have 21'' wheels.

I'm running them at 2.7 bar all around (39 psi)

According to the pcm, I should be running 2.3 bar (33 psi) in fronts and 2.5 bar (36 psi) in the rears.

I don't know... Feels a bit low and doesn't match the numbers other members have posted here. Seems to me like the pcm generates a random number for each car. Why isn't it the same for everyone?

 

[simcity]

So, safe to say that the dealer put in too much air and I should let some out, or do they know something that the app/car doesn’t?

21” Mission E wheels.

For what its worth my plate here says 41 psi all round on part load (2 people) and on full load (2 people + luggage symbol) its 43 psi up front and 45 psi on the back.

Pirelli PZeros on 21" Spyders

 

[simcity]

I don't know... Feels a bit low and doesn't match the numbers other members have posted here

Seems like we discuss this topic every couple of months and draw the same conclusion....see my last post in this thread:

https://www.taycanforum.com/forum/threads/tire-pressure-question.15330/

??

 

[tchavei]

Seems like we discuss this topic every couple of months and draw the same conclusion....see my last post in this thread:

https://www.taycanforum.com/forum/threads/tire-pressure-question.15330/

??

Yeah, I was actually re reading that thread. I'll just keep it at 2.7 bar /39 psi better a little higher then too low.

 

[simcity]

Yeah, I was actually re reading that thread. I'll just keep it at 2.7 bar /39 psi better a little higher then too low.

It’s a really interesting thread that one.

Just shows how much factory plate variation there is with otherwise the same size tyres / wheels. It’s clearly model / variant / spec / options and hence suspect then final weight and weight distribution dependant. Glass roofs weigh more than ally. RAS is different to non RAS etc etc

Why would Porsche otherwise go to the bother of fitting plates with all these different settings on them….

 

[whitex]

Ok, so I adjusted my tire pressure using the differential pressure it was showing. It worked to show +0 for all tires. Then temps warmed up, and the tire pressure showed +1 again. I left it alone, thinking maybe rounding error. Then it got really hot (>80F) and pressure started showing +0 again (on all 4 tires). It cooled off somewhat (58F outside right now, car in garage showing 64F), the car shows the tire pressures from 15hrs ago show +0 at 33psi even though the expected cold shows 35psi all around

while the plate shows this:

Worth nothing, the all-seasons is what came from the factory with the car (I speced them).


So, following the yellow sticker above, we are supposed the label on the car, unless we want better driving comfort, in which case we are supposed to be using the user manual, which says to adjust the tire pressures as per differential pressures showing on the instrument cluster or PCM (see red text below).

So it seems you just have to follow directions and read stickers, manuals, and car screens.

 

[Scandinavian]

It’s a really interesting thread that one.

Just shows how much factory plate variation there is with otherwise the same size tyres / wheels. It’s clearly model / variant / spec / options and hence suspect then final weight and weight distribution dependant. Glass roofs weigh more than ally. RAS is different to non RAS etc etc

Why would Porsche otherwise go to the bother of fitting plates with all these different settings on them….

It is interesting that so many variables influence the specification for the tyre pressure. My concern here is that, with so many different Specifications, will this make future SW updates more complicated?? It could be that depending on specification, glass roof, RAS, 4S, Turbo, other options, each VIN number would have a unique total SW package??

Look at the celebration when they had produced 1 million 911 and stated that no two 911’s had the same specification!

That would be a nightmare in the SW build if they have to test a hell of a lot of combinations before release?

I can understand that, with the same mission e wheels, there could be a different recommendation for say Pirelli or Good Year tyres. But what if I switch from Pirelli NF0 to Good Year NF0. Or to a new release NF0 tyre. some Have reported lower front tyre pressure and higher rear pressure on the same Turbo model. A difference of 0.1 and 0.2 bar??

But I take my hat off for Porsche if they have spent time testing and trying out all of these combinations??

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