I think you are right to start assuming tires, tire pressure and weather changes if it's a pulsing that appears to coincide with tire rotation that increases with speed. How many miles? I've heard of new rubber on tires being a little more noisy as they start to get used. Are you sure you don't have an acorn or rock stuck in the tread?I apologize in advance if this is a highjack....
My brand new 2021 EX Nightfall with AWD has a sort of "pulsing" going on in the rear end. It's not so much a vibration, although there might be a minimal amount. It's more of a sound, that increases with speed. It's present in some form at all speeds. It's not very loud, and the stereo and road noise drown it out.
The low tire pressure light tripped with a recent cold snap (Florida). I added a little air but now that it's warmed back up outside, the pressure is high. I'll drop the pressure to see if it has any effect.
Any other ideas?