Like others have posted, I would replace that rear tire also. When the front tire came off the entire weight of the rig on that side was supported by that single tire. It is probably internally damaged.
It's odd that I've never seen tires come off a traveling vehicle before this past year. However twice now within the past few months I've seen that and that's a real scary sight ! If one of those free wheeling tire/rim combos struck another vehicle, there for sure would be tremendous damage/injury to whatever was in its path.