I have one bike; a cross/gravel bike that acts as my do-it-all bike. I tend to just change tyre pressure depending on what I'm doing. I use schwalbe landcruisers - 40mm up front, 35 up back. If I'm doing a longer road ride I usually pump up the PSI to around 60-65 on both tyres to roll better. If I'm heading up the pentlands or going off road, I'll drop down to ~39-40PSI on the front and 43 on the back, which gives me enough grip. I've found that when riding with the lower pressure, I generally stay comfortable and happy for longer. Even with the bumps and roughness that comes with off-road riding on a rigid bike, my back particularly is usually fine. I'm finding that on road rides though, even when the ride is more smooth, I get tired quicker and my back gets stiffer quicker. I'm starting to wonder if this is due to my tyre pressure. My question is; is lowering tyre pressure for longer road rides a thing? I'm planning on doing a 40 miler tomorrow all on road, and am considering bringing the pressure down a bit to see if that helps, but don't want to do it if the comfort thing is all in my head and I'll just be making the ride draggier for no reason.