I know I should use a pyrometer but mine got stolen and I am not sure how often I am going to track my car so....back to the tire pressure method.

Running Falken Azenis street tires (265 front, 315 rear on 18's) on my car and just want to burn them off. Been running around 40psi hot and trying to see if that is normal for this car. This is my first Porsche and all cars have different hot pressure limits for the track.

Whats your experience on street and track tires?

 

Really depends on the tires you are running because each have their own sweet spot, but usually around 34-36F, 36-38R. I think Hoosiers are lower. 40 psi on my car makes the tires greasy with less grip, but that is on Rcompound rubber.
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Yeah. I haven't run street tires at the track in a very very long time. So I am in the dark here. Plus, with these cars and the weight in the rear and all the heat that the engine generates I am not sure if the pressure should be staggered like you said or the same all around....

 

Depends on setup. No one set of pressures fits all. Start them off at 36/38 a play from there.

 

Street tire hot pressures are usually in the high 40's. Street tires don't like heat so if you want decent grip you have raise the starting pressure so that you can come off the track in the high 40's. With that said every car, driver and driving style is different - don't drive over your head. If it doesn't feel right, make changes until it does. Keep data and learn your car for you!

 

When I ran Nitto NT01s in a 245/40/18 and 315/30/18 I liked 33/37 hot.
I am now running NT01s in a 245/40/18 and 305/35/18 and find the sweetspot is 33/35 hot. I am absolutely thrilled with the taller 305/35/18 as it provides better grip and does not roll over nearly as much as the 315/30/18. Awesome tire!

 

Do you run awd? Assuming you still run the 245/40 in front, that's a 3.5% difference in diameter F/R with the 305/35. Isn't that too much for the AWD differential to handle?

 

RWD. With AWD and a 3.44 final drive ratio on both ends, your rears must rotate a little faster than the fronts for any torque to be transferred up front through the viscous coupler. Thus the requirement for same size tires or rears just a hair shorter than the fronts. Not sure where the mythical 3% rule comes from.