Tyre Pressure - whom to believe?

[tophamn]

What is the symbol top left?

I think it means for the whole speed range - some cars show increased pressures for higher speeds.

Sponsored

 

[chun]

In September they advised me 2.8 all 4 corners; on a turbo.

I have been driving anyway at 2.8-2.9 at all 4 corners, and have seen very little tire wear over 7000+ km

 

[unbiased]

I would think the sticker is the most accurate one because the pressures are probably tire manufacturer specific to a certain degree, or am I wrong on that one?

 

[Scandinavian]

I would think the sticker is the most accurate one because the pressures are probably tire manufacturer specific to a certain degree, or am I wrong on that one?

At an earlier stage we concluded in the forum that the sticker values, for same model year, varied depending on tyre manufacturer. Pirelli could have a different sticker value compared to Good Year.

I would have thought that Porsche used the OCM and tyre pressure monitoring system to give the correct value in the car. Depending on options included and tyre manufacturer. They could then easily via OTA update the values to current ones, should they find new data to support new NF0 approved tyres.


Oh wait! Porsche and OTA! Not gonna happen!

 

[jadatis]

Main goal of tyrepressure -determination is to give the tyre a deflection that wont overheat any part of tyre-material when driving the speed constantly, for wich it is determined.

Deflection is made by the load on tyre ,and pressure in tyre.

On the plate the normal use ( 2 puppets) , the axleloads are determined by carmaker , and for fully loaded the max permissable axleloads are used to calculate the needed pressure.

But Porche and BMW give calculated recomended pressure for the setting on tpms screen ( comfort, sport eg) calculated from 20 degrC to the temperature in tyre, also sended by the sensors.

So its yustvwhat the engenears thought needed .
If you can determine the axleloads in your use 99% acurate, wich is the most tricky part, and your responcibility, I can calculate a pressure for that. Also need max speed you use, and wont go over for even a minute.

You can add upto 10% to the axleloads, and take 20 kmph higher speed, and still comfort and gripp aceptable.

This story explaines the different recomended pressures, yust what they think is needed.

 

[Glygoo]

My 4CT sticker says 38psi front, 34psi rear.

 

[Bennachie]

Mine is CT and 39R/37F.............

 

[chun]

On my CT I have 2.6 2.3 with 20”.. difference at the rear.

its also odd how a Tesla 3 same wight double motor with something like 150kg less requires all wheels 2.9bar!
I reckon suspensions have a big play in it..

Thats with winter tires, no? Lower pressure is understable, for more traction & more safety.

Tesla recommends 2.9 all 4, on 21 inch, for increased range.

I would not trust what it says on the pillar, as they have updated their recommandations in the manual at least 4 times. I would suggest following the manual, in which case 2.7 front and 2.9 back or 2.8 across all 4 is the latest recommandation - 21 inch.

For winter I am also on 2.6 & 2.3 on 20 inch; not what I would like myself, but it is what the dealer recommended me for increased safety

 

[figure1a]

Do the PCM. There you select wheel size, tire type and load. I feel that is the most accurate.

Sponsored