I have 12R22.5 tires, no spare. My son and I tried to take off a front wheel so we could change an air bag. We farm, and have a pretty good assortment of tools. We used a 1" drive socket set, with a 3' handle. We then put a 2' extension on that handle. We both were on that 5' handle, and could not break a single nut loose! So, we gave up, and changed the bag with the wheel on!
There is NO WAY we could change a wheel on the side of the road. A rear would be harder, because of how far the studs are recessed.
There is a space on the roof of the DP for a tire mount. I am thinking that when I change tires, I will put an unmounted tire up there with a front end loader. As it is a 12R22.5, it is NOT a common tire. So, if needed, a road side tire truck could get the tire down, and mount it on the wheel with the problem.