Either that, or you leave home with new tyres, and carry an extra set with you, and hope that´ll get you far enough, where you can find suitable tyres again. Doing some research should point you to a tyre, that´ll have long enough mileage (.....in fact the mileage of some new tyres, like 15-25 k kms from a rear, might mean that you don´t even have to think about carrying spares any more).

So, is carrying spare tyres needed in the first place, is another good question, and that depends on many things, but at least it is possible on most bikes. I´ve personally carried a whole set for about 30 thousand kms, while travelling two-up.

I suppose this depends on the type and size of the tyre you wish to ride on. Carrying a spare set around the sorts of distances you described I would imagine is not ideal, but if you were not convinced you could get any more rubber en route, then your choice is made for you. Travelling two up will of course decrease the mileage you are likely to get out of (A rear at least) a set of rubber, so that would be a consideration. I suppose in an ideal world, having a "Full test", i.e. riding fully loaded on your chosen rubber until they require changing will give you vital info about tyre wear and life span. I accept however this is an unlikely proposition for most though.

This is how we carried our spare set (the pic is from Iran on the way to India actually, that´s why my GF is covering her hair):



We added home-made parts to the bike´s crashbars to ´hook´ the tyres on. I had lots of doubts about it first, and even after the first test rides, but in the end it actually worked really fine for us. There was NOT many extra centimeters of space available, though, both tyres were resting against my knees in riding position (actually that was comfortable – and I got so used to it, that when we rode without the spare tyres, it felt very strange!). And the front wheel of the bike could touch the spare tyres, if tilted to the extreme left or right. It will depend on the bike model, if you´re able to carry them on the sides or not. If I was not able to carry tyres like this, when traveling two-up, then I probably would not have carried them at all.

In fact we saw another V-Strom in eastern parts of Turkey, but the next one after that we probably saw in Australia, over 20.000 kms later. With this setup, I never had to look up for tyres anywhere after leaving Greece, but it appeared to me, that for these wheel sizes (same as most big GS´s for example) tyres were not widely available. Maybe you could find something in the big cities, but I was glad, that I did not have to search as when on a bike, I´ll preferably stay as far from the big cities of Asia as I can!! I´m sure somebody has a different view on this.

BTW, on this trip, we got about 16000 kms out of each set of Michelin Anakee I´s. I was positively surprised about that, as the bike was very heavily loaded, and most of the time the temperatures were also +30C and up on the daytime. Front and back were finished at roughly the same time. We used a maybe 10% higher pressures compared to the recommendation.

(sorry, this went a bit off-topic!)