This doesn't surprise me at all.

 

I was talking with my race shop about this a few weeks ago. The lower the pressure, the more of the tire stays in contact with the road surface as the sidewalls flex more thus more grip generated, but you have to learn to feel comfortable driving like that, because the lower the tire pressures the more wishy washy the car feels and less responsive it is, especially on initial turn-in. For most (myself included) even though there is more grip avail. I just don't like the lazy feel of the car.

 

According to Porsche manual and Service Manager it recommends to view the second screen that shows all four tires - + values . If values are 0 then that the correct pressure , If the values are a - or + then air needs to be added or removed . GO FIQUIRE

 

Where do you access this menu??

 

TPMS menu in the instrument MFD.

Look in your OM.

This is how you adjust pressure...it's temperature compensated.

This is for regular road use...track use discussed above.

 

The tire pressures indicated on the door sticker are often incorrect.

The Owner’s Manual states the correct cold tire inflation pressures for normal driving.

They are:
29 psi Front
33 psi Rear
(See attached.)

“Cold” means ambient driving temperature before driving begins when the car has been at rest for several hours. If there is a difference in air temperature between where the car is stored overnight and the outdoor ambient temperature where the car will be driven, then the setting of the “cold” tire pressures needs to fluctuate accordingly before drive-off.

So if your car is in a heated garage overnight at 75 degrees but it’s only 50 degrees outside, the cold tire inflation pressure would need to increased to compensate for the loss of pressure due to colder air. In this case you’d increase all values by about 3-4 psi. I imagine there’s a chart for this.

Same applies in warm climates where the car might be stored in an air conditioned garage.

I have never heard of lowering tire pressures if driving hard or fast. On the contrary, German manufacturers expect their cars to be driven at autobahn speeds and therefore they often list tire pressures suited for high speed driving, which usually consist of at least 4psi added to the stated inflation values for normal driving. Higher consistent speeds such as 100+ or 130+ require more inflation pressure. While Porsche has not done this (lately) in their Owner’s Manuals, I can say for sure that Owner’s Manual after Owner’s Manual lists (higher) inflation pressures specifically for high-speed driving.

I am not speaking about track driving here. Inflation pressures on track, as with just about every other performance setting on track, fall into the category of “deep dive pick your preference track setting.” Considerations of art, feel, rule of thumb, and personal preference apply when the discussion is about settings for track driving.

For street driving, this matter is a matter of fact rather than a matter of opinion, as long as we agree that we should do what the car manufacturer says and we correctly apply the mathematics involved.

 

Definitely have had to lower pressures while driving spiritedly in the mountains. Pressures can rise pretty quick and the Cup2 tires get loose at the higher pressures. PS4's handle pressure increases much better than the Cup2 and have less of a need to reduce pressures.

 

My pressure was going up 8psi during hard mountain driving. The tires get finicky at that high of PSI in my experience.

The handling feels much better around the 30/35 mark.

 

Yes but all that heat and rise in pressure are factored in by the engineers at Porsche and Michelin. They state a cold tire pressure and the subsequent increase due to temperature is acceptable. This is why they recommend (or require) higher inflation pressures at autobahn speeds — they wouldn’t recommend those if the increased pressures would result in lower grip levels or danger to the tire.

Fact is tires need more pressure under high stress conditions. Like deflating a football, there might be a handling advantage but there will be a structural and wear-and-tear disadvantage.