In all my years of rv'ing, I've only had one blowout on the rv and that was a small pop-up (which did have a spare) many years ago.
Since that time I've had two travel trailers and two motor homes and have not experience any tire problems. Both the mh's had the larger 22.5" tires and I really did not have any space to store the tire, much less a tire and rim. In addition, there is no way I (by my self) could actually change the tire. The weight (100 lbs plus) of one, and the extreme amount of torque the lug nuts are tightened to, totally eliminates my ability and equipment.
So, if I ever have a tire problem, I will rely on my ERS to take care of me. I realize I will pay a premium price for the replacement tire, but that is an expense that I have figured into the equation.
Ron