My tires came with 45psi at delivery - and they had driven it 200 miles to get it to my dealer! I removed the excess air myself right away. The dealer's PDI didn't bother to.
I bought a cheap digital gauge and it reads exactly what the dash reads.
I try to keep mine at 32 cold. During the summer I've seen them go up to 37 when very hot, and on our coldest morning I've seen them at 29.