Donut spares - buy from a junkyard?

[atikovi]

All these post on donuts say they are only good for a few miles, here is what my owners manual says for my Buick.

Just bitog rumors based on opinions and guesses, not real facts. No manufacturer is going to have a tire that's so fragile it only lasts a few miles. Like all tires, they are good until they have worn out, which for donut tires are thousands of miles.