Is there a valid reason to carry the extra weight of spare tire? Will roadside assistance show up with tire mounted to wheel and then change it? There is no way I could change it myself.
Road service can bring a tire to mount on your rim. It may or may not be the same type as your other tires. That depends where you are when you break down and what tire stores are open if it is a weekend/Holiday. I carry an unmounted spare just so that I can speed up the whole process and get back on the road. I only have to wait for the road service to show up.