Ideal tire pressure for long trip

[Midzmerchant]

Hi fellow taycanians!

I am going on a long road trip of 650 miles. I just had my tires replaced recently.
I wanted to check what would be the ideal tire pressure for my 23 taycan GTS with 21 inch wheels. The sticker says 41 front 45 rear but I am not sure if there should be an adjustment if I have car with moderate stuff I’m carrying and if the pressures should be a little lower to prevent overheat and further issues with wheels especially I’m going 80-85 for long periods of time. Let me know please. Thanks

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[SoccerMan94043]

I just split the difference between loaded and unloaded as a happy medium for all occasions: 39 front, 41 back.

 

[f1eng]

Lower pressures are worse if loaded and going at higher speed.
I run my 21" tyres at the loaded recommended pressure for long runs.

 

[Tooney]

Use the TSB not the door frame sticker. https://static.nhtsa.gov/odi/tsbs/2026/MC-11027133-0001.pdf
TSB info ought to be in PCM as well.

 

[Flying ace]

Use the TSB not the door frame sticker. https://static.nhtsa.gov/odi/tsbs/2026/MC-11027133-0001.pdf
TSB info ought to be in PCM as well.

This, I use this table. It's also published in your e-manual. For my trips, I typically go with 5-seater full load (most trips are packed vehicle). Hot tire pressure does get uncomfortably high in hot climates, and I tend to adjust down to the halfway point between partial load and full load.

Monitor your pressure in hot climates and ensure it's not approaching tire's max pressure limit published on the sidewall

 

[jadatis]

Found in link of post #3 from Tooney, that 21 inch where only in front 265/35ZR21 101Y XL
Is maxload 1819 lbs AT 42 psi upto 160 kmph/ 99 mph.
Rear: 305/30 ZR 21 104Y ZR
Is maxload 1984 lbs AT 42 psi upu 99 mph.

Officially Y speedrated maxload is given for the referencepressure of 42 psi upto 220 kmph/ 137 mph, then for higher speed the 42 psi has to be highened up with a complicated system.
but keep it on 99 mph.
I use a simpler and better system for higher speed, looked off from LT and trucktires.
So I you drive faster then 99mph, even for a minute,I can make a list for that speed.

So check if you realy have these tires.

Then if you dont only promess to drive not faster then 99 mph, not even for a minute, but also dont do it in practice, you can use my made cold pressure ( at 20C/ 68 F ) / axleloadcapacity list with build in maximum reserve, at wich comfort and gripp is still acceptable. For that I give 90% of calculated axleloadcapacity for the cold pressure.


Then you " ONLY " have to determine the axleloads in your use 99% accurate, the most tricky part and your responcibility, and search them back in my list for the needed cold pressure.
If you know empty weight , GAWR'S and GVWR, and the way you load it with persons and gargo, you can dangerously estimate the axleloads.

Porsche gives on tpms screen besides the actuall pressure, the recomended pressure for the setting, calculated from index temperature of 68 degrF, to the temperature in tire, also receved from the sensors in tires. This gives the possibility to fill at a tankstation warm, yust read pressure between brackets, and adjust pressure to that.

So never blead down warm or cold pressure on a 100 degr F day, even if above max allowed cold pressure of 51 psi on sidewall.

101Y XL/ at 68 degrF / 104Y XL
Frontaxle/ cold psi/ rear axle
1541 lbs/ 18 psi / 1681 lbs
1615 lbs/ 19 psi / 1761 lbs
1689 lbs/ 20 psi / 1842 lbs
1762 lbs/ 21 psi / 1922 lbs
1835 lbs/ 22 psi / 2002 lbs
1908 lbs/ 23 psi / 2082 lbs
1981 lbs/ 24 psi / 2161 lbs
2054 lbs/ 25 psi / 2241 lbs
2127 lbs/ 26 psi / 2320 lbs
2199 lbs/ 27 psi / 2399 lbs
2272 lbs/ 28 psi / 2478 lbs
2344 lbs/ 29 psi / 2557 lbs
2416 lbs/ 30 psi / 2636 lbs
2488 lbs/ 31 psi / 2714 lbs
2560 lbs/ 32 psi / 2793 lbs
2632 lbs/ 33 psi / 2871 lbs
2704 lbs/ 34 psi / 2949 lbs
2775 lbs/ 35 psi / 3027 lbs
2847 lbs/ 36 psi / 3105 lbs
2918 lbs/ 37 psi / 3183 lbs
2989 lbs/ 38 psi / 3261 lbs
3061 lbs/ 39 psi / 3338 lbs
3132 lbs/ 40 psi / 3416 lbs
3203 lbs/ 41 psi / 3493 lbs
3274lbs/42 psi/3571lbs/ referencepressure


3345 lbs/ 43 psi / 3648 lbs
3415 lbs/ 44 psi / 3725 lbs
3486 lbs/ 45 psi / 3802 lbs
3557 lbs/ 46 psi / 3879 lbs
3627 lbs/ 47 psi / 3956 lbs
3698 lbs/ 48 psi / 4033 lbs
3768 lbs/ 49 psi / 4110 lbs
3838 lbs/ 50 psi / 4186 lbs
3908 lbs/ 51 psi / 4263 lbs/ often maxpress on sidewall

 

[acull2000]

Agree you should follow latest TSB. Please note the TSBs are regularly updated, eg:
https://www.taycanforum.com/forum/t...l-catastrophic-tire-failure.16788/post-484831

Remember these are minimum pressures - so anyone splitting laden/unladen pressure will be too low if you have 3 people and a couple suitcases get it. (For this reason I run full laden pressure all the time)
https://www.taycanforum.com/forum/t...l-catastrophic-tire-failure.16788/post-511682

Also note the pressures are minimum cold pressures (eg when you come to car haing not been driven overnight). Same as the 'maximum pressure' (often 50psi) on the tyre sidewall - this is the maximum static cold pressure. Going a little over this in running is fine.

 

[jadatis]

I once asked Porsche dealer about the settings.
Modern Porsche's you can set 2 things in the system.

1. Comfort or standard
Standard is for max technical carspeed, so higher pressure needed.
Comfort is for lower speed , I think 160 kmph/99 mph, but can also be the referencespeed of Y speedrated of 220 kmph/ 137 mph. Then on screen a warning when this speed is exeded.

2. Loadsetting
A. Fully loaded, for wich Gawr's/ MPAW's are used. But mind that a fully loaded car can be overloaded on rear-axle, forbidden, but if then pressure is to low, you also risk tirefailure by overheated tire-material.
B. Partload, for wich carmaker mostly determine expected axleloads for 3 persons and a little load.

So in total this can give 4 ( x 2 axles =8) different calculated recomended pressures, the tpms system assumes for cold measured ( when temp in an out tire rhe same, so ambiënt) at 20 degrC/ 68 degrF.

Then on screen, as already explained in former post, they let this recomended pressures change with temperature in the tire, on screen.

You could do this all yourselves eventually with rule of tumb calculations.
Then you can specify for your determined axleloads.
And max speed used, you wont go over for even a minute, is a matter of controling yourselfes.

For max speed a rule of tumb system of 1 loadindex step change per 10 kmph/ 6.2 mph different speed.
So here for rear 104 loadindex is for 99 mph , but if 190 kmph is your max used speed ( wich you wont go over for even a minute) you have to substract 3 loadindex steps , so 101 loadindex to use in the calculations.
Then in my list you can look in my made front list , that is why I used it as example.

The official system for higher speed is highening up the reference-pressure with system depending on speedcode.
Once made a graphics of it with paint, and later added psi and P-speedcode, and mph.
See how complicated, and V,W and Y also maxload lowering from 30 kmph below max speed of speedcode.

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