I had exactly the same thing on my Sduro Trekking. The tires are Engergizer Pro's with Green Guard anti-puncture technology. I had decided to try and run them at the minimal rated PSI (50), but soon discovered that this made the tire's behaviour become highly unpredictable in tight turns with a compression. For example, if I make a sharp turn after a speed bump with low PSIs, the adherence will brutally drop and I will suddenly find myself falling into the side I'm leaning towards. I've upped the tire pressure to 75 PSI and it's noticeably better. I have a lot of tight turns to take, many of which are banked on downhill streets or on cobblestone, so adherence is actually much more important to me than rolling resistance. I think that the Green Guard protection alters the way the tire behaves and makes it unsuitable for lower PSI. The Green Guard is a fairly stiff band that surrounds the tire, but the tire walls are soft and malleable in comparison. So this means that the tire needs to be run at a minimum PSI for it to perform well when it's running on its edge. I also found that the Energizer Pro handled poorly with lower pressure when taking large horseshoe turns at higher speeds (50km), which is a frequent scenario as I have many downhill exchangers that are S shaped. All of this is for the 38C size tire. The larger 45C can be run at a lower pressure and seems a little more versatile.
I realise that your R&M's tires are much fatter and of a different size, but I think you should try playing with the tire pressure a bit. In the end, you might find that you need different types of tire pressure depending on a particular usage. If I had straighter roads with more off-road usage, I'd probably pull out some PSI again. But for my usage higher PSI is much safer.