BLOW OUTS!!!
1. Buy a Emergency Road Side Assistance policy. There are a couple out there, i.e. Good Sam, compare a couple of policies and then pick the one you like. Do no recommend "AAA" RSA plan as it is not specifically designed for RV's and has various limitations and services which are not uniform in all states.
2. Throw that spare away today!
3. I buy new tires between 4 & 6 yrs. regardless of their condition After 3 to 4 years, if I am planning a long RV trip across the U.S., I buy new tires!
4. Go to Camping World and buy a tire changer device. You place it under the good tire and roll forward or backward and the bad tire is then off the ground ready to change. No more jacks!!! Changing tires along side of the road is not my idea of fun:) unless you are way out in the boonies and ERSA is going to be 3 to 4 hrs. away:)
5. Blowing Tires or tires coming apart on RV's is in general not as common as in your personal experience. No way to give a accurate predication but in my own experience, I expect 1 every 7 years. I tow a 15K 5th. wheel. I think your experience was just an anomaly and not a real preview of what you can expect with new tires. If possible go to a 16' rim and "E" rated tires. I have have had good luck with Good Year "G" rated tires.