Re: Tyre Pressures
I would agree that anything around the 36psi or more would be more than acceptable. What ever you prefer for a compromise between comfort and handling. It depends on the type of driving and the distance your are going to travel. Long runs go to higher pressure.
I run 36psi all round on the spider, then bump it up when going on a run along the coast.
On all the Alfa's in my family; 156, 147 and spider 916. I have always rotated the tyres at about 10,000 km. I have changed all the tyres to either Maragoni Mythos or Pirelli P7 or Zeros and the tyre life I get is between 40,000-60,000 km. Tyre pressures and alignment is critical to a long life. Sorry to state the obvious.
On Pressure gauge, I invested in a stick/ pencil type gauge rather than a cheaper dial gauge,cost about $40 (australian). Checked it at work against a calibrated gauge and turns out to be accurate within 0.5 psi. ( Made in England no less).