Hi Martin,
What do you think about the Schwalbe Big Apple? 26 x 2.15" for 615gr of memory.
It is not slick as the Supreme and relatively light.
Always in a spirit for ride in all condition, rough and asphalt roads, wet and dry weather..
According to the Schwalbe website the Big Apple 26 x 2.15" in the "Performance" line is 710g, not bad for a wire bead tyre. Heavier at 920g in the "Active" line, and probably less durable as well.
I've not had much experience of Big Apples, just got the 20" x 60 mm version on my trailer, where it is much better than the old moped tyres I had before.
To me, it looks relatively fragile compared to the Supreme and Dureme. The slick tread of the Supreme doesn't bother me, grip seems pretty good wet and dry on tarmac, and I'm not sure the Big Apple will do any better off road, except on loose surfaces like sand where the extra width of the 2.15" will help a bit. There is also a 26 x 2.3"/60 mm version of the Big Apple, which should do even better on loose surfaces if it will fit under your mudguards (it should fit OK in the Nomad frame and forks), the weight of this one is given as 780g.
With my Raven Tour, 55 mm is about the maximum I could fit while leaving adequate mudguard clearance. For mainly tarmac use with not too much off-road I intend sticking with 50 mm Schwalbe Marathon Supremes while I can still get them.
If I have the chance to do a tour involving more off-road riding I will use my 50 mm Duremes. If/when these are worn out my current choice for replacement would be the Marathon Mondial if it is still available, if possible the widest that will fit (so 2.15"/55 mm if I bought them today).
Comparing 2.15" Big Apple to Mondial, Big Apple is cheaper, rolls slightly better on tarmac (4.5 as compared to 4), and weighs less at 710g compared to 865g. The Mondial is (according to Schwalbe) better for on and off-road grip, protection and durability.