Porsche Cayman Owner's Manual page 301

Tire pressure for cold tires
Summer and snow tires
17 inch and 18 inch wheels
19 inch wheels
These tire pressures apply only to the tire makes and types approved by Porsche.
Please observe the chapter "TPC TIRE PRESSURE MONITORING" on page 122.
Please observe the chapter "TIRES/WHEELS" on page 237.
front 29 psi (2.0 bar)
rear
36 psi (2.5 bar)
front 32 psi (2.2 bar)
rear
36 psi (2.5 bar)
Vehicle Identification, Technical Data
299