Tire pressure fill info and questions
08-02-2018, 09:27 PM
#1
Tire pressure fill info and questions
My turbo has different size tires.
Front: 255/40 20"
Rear 295/35 20"
Car is set for partial pressure, standard, faster than 100mph, summer tires.
What you you folks set these tire pressure at?
The sticker at side of the door frame driver side, states partial pressure should be 44psi in both front and rear.
The multi function display shows that for cold tires to be filled right (per above settings), fronts have to be inflated to 44psi, rears inflated to 38psi.
This way fill info shows 0mpsi needed in tires.
Max tire pressure is 49psi, so I am starting to think 44psi may be high.
Also, is there a way to reset the display to show full pressure at differently set levels from the 38/44 psi?
Wanted to hear advice on how to set thgem right.
Front: 255/40 20"
Rear 295/35 20"
Car is set for partial pressure, standard, faster than 100mph, summer tires.
What you you folks set these tire pressure at?
The sticker at side of the door frame driver side, states partial pressure should be 44psi in both front and rear.
The multi function display shows that for cold tires to be filled right (per above settings), fronts have to be inflated to 44psi, rears inflated to 38psi.
This way fill info shows 0mpsi needed in tires.
Max tire pressure is 49psi, so I am starting to think 44psi may be high.
Also, is there a way to reset the display to show full pressure at differently set levels from the 38/44 psi?
Wanted to hear advice on how to set thgem right.
08-03-2018, 08:50 AM
#2
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I run my 20s and 21s at 35 psi in comfort pressure so the light goes away. I don't mind if the warning goes on when I pass 100mph. I think 44psi cold is too much, but I suppose that's what Porsche confirmed to be safe at max speed fully loaded.
08-03-2018, 10:01 AM
#3
Why not set to recommended tire pressures? Is the ride too harsh? With cold tire pressures set at 44psi for rears, I've seen it go up to 51psi (per display) on a hot day. The car is heavy and probably the reason for the higher tire pressures. Under-inflation or over-inflation will have consequences over the life of the tire. Like, excessive inner/outer tire wear, excessive center tire wear, side wall flex, affects handling or more heat build up.
I've not seen a way to change the expected tire pressures aside from configuring the tire pressure based on tire size, tire type and load.
I've not seen a way to change the expected tire pressures aside from configuring the tire pressure based on tire size, tire type and load.
08-03-2018, 10:24 AM
#4
We had a thread just the other week about this here .
Evidently the difference between the door sticker and the MFD are due to full vs partial loads, So indeed, the full load pressure of 44 psi may be a bit high for everyday driving with one or two people and a empty cargo area.
Evidently the difference between the door sticker and the MFD are due to full vs partial loads, So indeed, the full load pressure of 44 psi may be a bit high for everyday driving with one or two people and a empty cargo area.
08-03-2018, 10:26 AM
#5
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Personally, I feel that when starting at 44 cold, the tire warms up to a pressure I feel is too high (upper 40s). The ride is harsher, the tire has less grip and I'm far from max load (1 occupant, no cargo 90% of the time). I find that the PSSs like the upper 30s when hot, hence why I set to 35 cold for the street. At the track, I start at 28 cold and that creeps up to mid/upper 30s warm.
With different tires, or if you drive with a full car and a loaded trunk, your ideal pressure might be different.
With different tires, or if you drive with a full car and a loaded trunk, your ideal pressure might be different.
08-03-2018, 11:53 AM
#6
We had a thread just the other week about this here .
Evidently the difference between the door sticker and the MFD are due to full vs partial loads, So indeed, the full load pressure of 44 psi may be a bit high for everyday driving with one or two people and a empty cargo area.
Evidently the difference between the door sticker and the MFD are due to full vs partial loads, So indeed, the full load pressure of 44 psi may be a bit high for everyday driving with one or two people and a empty cargo area.
Personally, I feel that when starting at 44 cold, the tire warms up to a pressure I feel is too high (upper 40s). The ride is harsher, the tire has less grip and I'm far from max load (1 occupant, no cargo 90% of the time). I find that the PSSs like the upper 30s when hot, hence why I set to 35 cold for the street. At the track, I start at 28 cold and that creeps up to mid/upper 30s warm.
With different tires, or if you drive with a full car and a loaded trunk, your ideal pressure might be different.
With different tires, or if you drive with a full car and a loaded trunk, your ideal pressure might be different.
08-03-2018, 03:19 PM
#7
With my setup, cold, per above I set:
Front: 255/40 20" - 38 psi
Rear 295/35 20" - 44psi
This way, when I look at the fill info meter, each tire shows 0psi (means tire pressure right on)
When I do this, with setup set for summer tires, part load, standard (over 100mph), tires get up to:
Front: 255/40 20" - 39 psi
Rear 295/35 20" - 46psi
Given that my typical spirited run is on way to/from office, the temps do not vary that much, but still higher than I am used to
On my Cayenne turbo, the sticker shows both part load and full load, was easier.
I was hoping there is a set/reset mechanism to recode TPMS, to track pressure according to what you want it to be.
1. Is there a way to do this on the Panamera?
2. Fronts are different volume from rear tires, so I think there needs to be different setting for each, but what would be a good starting point? I do not think I will be doing any drifting, but want to avoid increased tire wear due to high pressure (or too low pressure).
Front: 255/40 20" - 38 psi
Rear 295/35 20" - 44psi
This way, when I look at the fill info meter, each tire shows 0psi (means tire pressure right on)
When I do this, with setup set for summer tires, part load, standard (over 100mph), tires get up to:
Front: 255/40 20" - 39 psi
Rear 295/35 20" - 46psi
Given that my typical spirited run is on way to/from office, the temps do not vary that much, but still higher than I am used to
On my Cayenne turbo, the sticker shows both part load and full load, was easier.
I was hoping there is a set/reset mechanism to recode TPMS, to track pressure according to what you want it to be.
1. Is there a way to do this on the Panamera?
2. Fronts are different volume from rear tires, so I think there needs to be different setting for each, but what would be a good starting point? I do not think I will be doing any drifting, but want to avoid increased tire wear due to high pressure (or too low pressure).
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08-03-2018, 03:41 PM
#8
I was just doing additional research on this.
Car assumes COLD means 68 F.
Where I live in Tx, temp in the morning is about 85 F during summer.
If my tire setup for Panamera turbo is:
- Standard (over 100mph)
- Part load
- Summer tires
- 20"
and if COLD temp at 68 F is declared to be:
- Front: 38 PSI
- Rear: 42 PSI
Then, at 85 F, the temperature should be set to:
- Front: 39 PSI
- Rear: 43 PSI
When I inflate my tires so Fill Info shows me 0 for each tire, I need the 39F/43R pressures set.
So looks like Porsche wants us to trust them with the setup, regardless of what tire gauges say.
They built in pressure changes into the algorithm, so I may need to start putting more trust into the system. No?
Car assumes COLD means 68 F.
Where I live in Tx, temp in the morning is about 85 F during summer.
If my tire setup for Panamera turbo is:
- Standard (over 100mph)
- Part load
- Summer tires
- 20"
and if COLD temp at 68 F is declared to be:
- Front: 38 PSI
- Rear: 42 PSI
Then, at 85 F, the temperature should be set to:
- Front: 39 PSI
- Rear: 43 PSI
When I inflate my tires so Fill Info shows me 0 for each tire, I need the 39F/43R pressures set.
So looks like Porsche wants us to trust them with the setup, regardless of what tire gauges say.
They built in pressure changes into the algorithm, so I may need to start putting more trust into the system. No?
08-03-2018, 05:37 PM
#9
Measuring cold tire pressure at 68F temperature would be under ideal conditions and ideal climate conditions. Just set the desired/recommended pressure when the tires are cold, regardless of the current temperature. You will need to check and adjust the pressure a few times a year due to seasonal changes. Otherwise, your tire pressure will be under-inflated or over-inflated across with the large temperature range throughout the year and possibly trip the TPMS warning.
As noted, my summer rears are set at 44psi. On hot days, cruising on long trips and loaded trunk, it typically reaches 49psi and as high at 51psi (100F+ outside temp). Tires will generate a lot of heat during operation (acceleration, braking, turning) and translate to higher pressure, PV=nrT. When you start a road trip from the northeast with temps in 70's and end up in the southwest with 100+ temps, it is not practical to continually adjust the tire pressures. The tires handle it just fine.
No way to recode the TPMS for the user to my knowledge.
I've had good tread wear with the recommended pressures and adjusting the pressure with seasonal changes.
More important, put your trust in a good set of tires. A good mechanical air pressure gauge helps, too.
As noted, my summer rears are set at 44psi. On hot days, cruising on long trips and loaded trunk, it typically reaches 49psi and as high at 51psi (100F+ outside temp). Tires will generate a lot of heat during operation (acceleration, braking, turning) and translate to higher pressure, PV=nrT. When you start a road trip from the northeast with temps in 70's and end up in the southwest with 100+ temps, it is not practical to continually adjust the tire pressures. The tires handle it just fine.
No way to recode the TPMS for the user to my knowledge.
I've had good tread wear with the recommended pressures and adjusting the pressure with seasonal changes.
More important, put your trust in a good set of tires. A good mechanical air pressure gauge helps, too.
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frederickcook87 (08-23-2023)
08-03-2018, 11:13 PM
#10
You are helping confirm my suspicions. I guess I will leave as is, front 44, rear at 38. Will just rely on the Porsche design.
Researched this and Porsche states their design is much more sensitive and accurate than gauges one can get in regular store.
Already have a good gauge with my shop compressor, but now am using the car Tire Fill multifunction display sub setting, to fill tires until all say '0' next to the tire icon.
Thank you very much.
Researched this and Porsche states their design is much more sensitive and accurate than gauges one can get in regular store.
Already have a good gauge with my shop compressor, but now am using the car Tire Fill multifunction display sub setting, to fill tires until all say '0' next to the tire icon.
Thank you very much.
02-13-2021, 05:03 PM
#12
Temperature variable
As the air in the tires goes up 10 degrees the pressure goes up about 1 pound. So don’t have the cold pressure too high.
I also have a 2007 C2S. Early in TPMS years. If I target what most say is a good highway pressure the damn thing says I have a flat when it’s cold. I run it a little high rather than having the warning light on. I had 3 gauges lab calibrated as I wrestled with it.
I also have a 2007 C2S. Early in TPMS years. If I target what most say is a good highway pressure the damn thing says I have a flat when it’s cold. I run it a little high rather than having the warning light on. I had 3 gauges lab calibrated as I wrestled with it.