I fitted a pair of Michelin Anakee adventure tyres. Just short of 5000 miles door to door. They still have enough tread for my next trip, Ireland via Scotland. Probably need new before the Alps in August though. Road only tyre would have seriously curtailed our trip as the main roads which are mostly in the valley bottom had been washed out, landslides, flooding etc. we did a good couple of hundred KMs on dirt, gravel tracks. The motorad tour was turning south because most of them had just road tyres. I would certainly recommend fitting tyres which can cope with at least gravel roads.
This washing out of roads whilst at the time slightly stressful was actually a good thing as we rode on tracks etc and saw things, places that we would have missed on the larger roads.
These washed out roads started from about Lillehammer North.