Originally Posted by
ItsJustMe
Bike shops, maybe. But not every town has a bike shop. If you shred a tire, you need one now. I've never seen 700c tires in Walmart for instance.
The touring journals I've read indicate that when you get down into little villages in Mexico and South America, you'll almost certainly not find 700c tires. Bigger cities will have a proper bike shop that may carry 700c tires.
I can't speak for SA as I haven't cycled around it that much. However, everywhere in Asia carried both 26"/-559 and 28"/700c/-622.
I can't remember the last time I was in a decent-sized town (bigger than 50k or so) in the US, without a bikeshop.