68 degrees at sea level. For every 10 degrees you vary by one pound and by every 1000 feet you vary by one pound.

The recommended pressures from Porsche are mainly based on mileage gains and not hoax performance.

Certain tires also work differently with different pressures depending on driving style.

Personally, I run Michellin Pilot Super Sports and like to maximize grip so I actually find
33/37 works best. This gives me a more balance over/under steer handling. It also gives me a little extra wiggle room on the twisties
Before they get too hot and get greasy.

 

Thank you for chiming in- are you running 305's as well?

I had my then 295's in the rears, and now 305's with also MPSS at the same 33/37 but when driving in SF increased the pressures slightly to help with the unavoidable potholes... Not sure if this is good practice, etc.

 

FYI, my rears are filled with regular air. They seem to increase by 3-4 PSI from dead cold to regular driving temp. The fronts are nitrogen-filled and they only increase by no more than 2 PSI.

I still wonder if the rears would stabilize with nitro.

 

Same observation here with psi increase to regular driving temps on regular air. I have no experience with nitrogen but would think the rationale applies to your rears as well?

What pressures are you using with your tire size setup?

I'm still trying to find the sweet spot pressures and playing around with them since I got back in the states..

I have 235's on 8.5x19 fronts and 305's on 11.5x19 rears. MPSS tires in Champion RG5's

Thanks