cause of blowout
I drive Semi, and have had blowouts several times. All GOOD tires, not recaps. It is amazing what hitting a piece of debris on the road can do to a tire, and you have no way of knowing what caused the blowout unless you see the debris. One blowout I had was a new tire that had less than 200 miles.
When You see debris, it is usually too late to avert it without going out of control. Swerving too sharply can be devastating. That is good reason to keep at least a 4 to 5 second safety gap between vehicles. You might be able to see debris in time to avoid it, but sometimes it is not very big, and unless you are VERY alert you won't see it anyway.
Spare tire is good idea, also towing and roadside repair insurance is advisable if you can get it.
I have Good Sam Club and had to be towed 2 times with my motor home.. Pays to be prepared, or you pay after the fact.
I'm glad you have an experience to talk about instead of being a casualty in the local news.