The terrain and weight of your vehicle will most likely determine whether you prefer super singles or rear duals. In general we traverse more sandy terrain, duals on the rear are literally a drag.
I had the choice of 19½" or 17" super single wheels when the truck was being built. As our travels will often be over interesting terrain, then the 17" tyres available at the time of purchase had a much larger tyre wall thereby allowing for greater deflation possibilities for rolling over sand, mud, corrugations thereby allowing the tyres to become a greater part of the suspension set-up in these conditions.
The 19" tyre choices while very good but extremely limited in Australia, are basically truck tyres that you can air down to a certain extent. No matter how far you air them down, their very strong sidewalls, which are very good in preventing staking and such, also lead to a harsher ride. I know this as one day out in the sticks I came across an almost identical vehicle to ours (NPS 300) with 19½" wheel/tyres. We went for short drives in each others truck, verdict, the 37" tyres were noticeably softer, not much, but noticeable.
The 17" tyres on our vehicle have softer and bigger sidewalls, which may lead to easier staking, I don't know whether that will be the case, but so far staking hasn't happened yet. When aired right down for difficult or interesting terrain, the ride is definitely softer/better. Traction is another enhancement possibility if you need to lower your tyres quite a lot for short intense recovery, the 17" tyre elongates further giving you great traction. Effectively, you require 1G down force or greater to retain traction up an incline, the lower you can air down, the easier one should be able to maintain the 1G down force to maintain traction; bigger sidewalls that allow the tyre to balloon more, really help here.
The downside to 17" wheels is a load restriction on the rear axle, we lose 500kg of load carrying capacity over the 19½" wheels. In our case it didn't matter as we are 1100kg under the plated limit, which is 7000kg and 1600kg under the design limit which is 7500kg when fully loaded and ready to roll.
Running All Terrain 17" wheels with 37 x 13.5" Gladiator All Terrain tyres. I'm not sure what you mean by outside tyre to outside of tyre, but our tyres are approximately 940mm high when on the truck measured from the ground.
Airing down at the start of a week of sand a fair bit deeper and quite harder than what you can see. 2.2 Bar pressure.
The second picture is where the tyres were getting great traction up a reasonably stony and slippery hill, 1.8 bar pressure.
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