On my BMWf650 I am running on Heidenau T60 (true 50/50 tyre) on the front and Metzler Lazer on rear. This is great for hardtop, but not so good for gravel roads. Since I shall be covering about 1000miles of gravel in Labrador, (Labrador Highway) I figured to take a rear Heidenau T60 to change on to when I reach the end of the tarmac at Pinware River.
When I get to Baie Comeau, Quebec, I'll change back to roadies until I get to Dawson City, where I can change for the 1000ml round trip up the Dempster Hwy. to Inuvik. Swapping tubed tyres is not difficult, and only takes 1/2 hour or so.
I expect that I will need a new road tyre by the time I get to Dallas, but a lot of the USA will be on The Great Divide Trail, so it maybe I will change both, but I will always travel with both types of rear, as carrying one spare tyre is not difficult, and the added grip when on gravel is a big bonus to me, not being very good at it
I know I can get Heidenau Tyres in the US, but am not so sure about South America. Maybe get someone to bring them out for me.