We prefer to travel the back roads of America and are sometimes quite far away from a facility that can change a tire, especially when out West. For this reason we always carried an unmounted spare tire that matched the other tires on the coach. Naturally I carry ERS but if it is going to be a long time for them to respond, I also carry the tools necessary to change my own tire. I do have 19.5 tires and while changing a tire I never have to lift the entire weight of the tire. From experience, I can mount a new tire in about 45 minutes, or probably twice the time an experienced roadside mechanic can do it. Not the most fun, but then neither is sitting at the side of the road waiting all day waiting on some service mechanic to show up with a mismatched overpriced new tire, or a mismatched overpriced used tire that MAY get me to a tire store.
If you always travel close to large metropolitan areas, that have lots of tire stores and service facilities, and if your specific tires are readily available, and if you never get a flat tire during a Holiday period, and if you only get flat tires in areas where you can pull off in to a safe parking lot, then you may not have any need to carry a spare.