boxsternewbie

Got the 958 turbo back from dealer and all four tires had been overfilled according to Cayenne. Did dealership screw up or is Cayenne wrong? They’re 295/35 r21 Continental DWS06. I’m taking air out regardless because the pig handles horribly when tires overfilled I’m just wondering why they did this.

Mrg02D

Pretty sure that’s what they are supposed to be at. Mine are around that.

leftlane

That has to ride terribly. I run the exact same tires and sizes and I keep mine at 35 front and 44 rear. Good wear and very smooth ride.

dimeadip

My dealer did the same thing to mine a couple months ago. I went by the specs on the doorsill and let the air out. Porsche did a lot of work to figure out the tire pressure, so I went with it.

deilenberger

There are different specs depending on the loading of the vehicle. The higher pressures are for a fully GVW loaded vehicle being driven at speeds in excess of 100MPH. That's unlikely to happen with mine anywhere in the US - so I used the part-load specs. These can be selected on the settings for the TPMS system along with summer vs winter tires and the tire sizes. Dealers are afraid of being liable if you have an accident due to underinflated tires so they always fill them to the maximum manufacturer recommended pressures.

marinerbc

+1. and in my case that was/is valid through 3 different cayenne at the same dealer in 8 years.

fatmatt0116

What a substantial difference this makes. I just changed my pressures to 36/44 and it is night and day as far as my back is concerned. My back thanks you. As long as the car isn't loaded up with stuff, it's safe to drive around with these pressures?

wkearney99

Here's what the manual says:

http://porscheownersmanuals.com/2015...ressure-barpsi



I printed out that table and keep it in the glovebox, with highlighter marking my tire size/types.

wkearney99

Depends on the rim/tire size combo. What are you running?

For normal driving it is unlikely to be 'unsafe' to have pressure vary by +/- 5 psi but may negatively affect your mileage and tire wear patterns. Too low and you wear the outside tread/sidewall, your mileage drops and steering gets heavier. Too high and you wear the middle of the tread, ride is harsh, mileage very marginally increases, steering gets lighter.. but braking and traction are impacted (as there's less tire patch on the road).

Mrg02D

Looks like I have something to try out today. Mine are set for full load, which I never am. What does the tpms settings do? Let the car know not to whine about low pressure?

My ride is pretty harsh over here in Baton Rouge. I’m new and have discovered that the roads are horrible and I’m really regretting not having air suspension now. Maybe adjusting pressure will help a tad?

F SANE IL

go in to the menu on the dash and check what tires they have set. if you're set to summer tires 21R and speed in excess of 100mph. this is the correct pressure. if you set it to comfort, you can lower the pressure and it will ride softer. I like stiff as bricks, mine is set this way.

wkearney99

I don't know what else the Tire options set. I'm assuming they affect the TPMS alerts, but there's also the traction control system and speedometer/odometer that are probably affected by it.

I have the PASM and PAS options in my '17 GTS and they do make a difference in ride comfort. On Sport+ mode it definitely transfers more road surface changes to the wheel. Comfort mode has quite a lot less of that but does not make the suspension wallow like a 60's era land yacht. Sport+ and high tire inflation will definitely feel harsh.

fatmatt0116

21” turbo ii wheels on Michelin summer tires on a turbo s. It looks like according to that chart I should actually go down to 39 for rears?

wkearney99

That's the chart for my 2017. I'd double-check if your model year is different. But, yes, it would seem that 48 is way too high for summer 21s.

fatmatt0116

Mines a 14, unlikely it is different.