I have a 2012 FLHX and I was running at 25 PSI from the dealer wen I bought it.....I was bottoming out a little on decent sized....drastic bumps. I went to the dealer and bumped it to 40 PSI and I think it rides really nice now!
The air shocks on the Street Glides do not have as much "travel" as the Ultras or Road Kings. They tend to bottom out faster than the others. (this I was told at dealership) I'm 200 lbs. at run my 2010 SG at 18 to 20....25 when 2 up. This for me seems to be smoother in all around situations. Hope this helps
It stays at 45 psi most of the time. I ride the bike solo quite often without lowering the pressure and it still rides good at 45 psi solo. Not as soft as 30 psi, but tolerable.