Class A coaches don't typically, if ever, come with a 'spare'... even a lot of newer cars don't, it's just not the issue that many folks 'fear' when traveling anymore, especially since newer coaches many times come with a year of 'free' roadside service.
Spare tires for larger coaches are very heavy, cumbersome, and not really even something you could even 'change' yourself, though some think that carrying an extra one would give them the ability to just hire a service to mount it... what most find out is that 22.5inch tires are very robust, and easily designed for the heat and weight that they are carrying.
Ours lasted for over 80,000 miles with little issues, other than some slight off-role on the fronts. Replaced them all with Falken RI150s last year, for another 80 thousand miles, or more, I expect, if not more.
You'll find that if you try to 'carry' a spare, you're going to experience a test of aggravation - 'where' would you carry it, store it, or mount it? Will it already be mounted on a wheel? If not, 'how' would it be mounted when you need it? Do you want it to smell up your storage area? Tires will do that. Even if you are determined to mount it to your rear, you may find that accessing your engine/oil/transmission fluids would be problematic.
The real chances of a 'blow out', or flat tire, is rare...very rare. So rare that carrying large 'extra' tires anymore is an exercise in futility.
'14 Palazzo 33.3 bunkhouse 34' diesel
KingTailgater2 Dish HD, 100w/5a SOLAR, BlueOx
110,000+mi since '14 - US, Alaska, Canada (also, '14 Gulfstream Amerilite and '07 ForestRiver Rockwood) : )b