Had a question from a friend about replacing both tires when one failed on the same side of the RV.
In Motorhomes with "Dual" tires (side by side) in the rear and you do not get the early warning from TPMS of air loss, you need to seriously consider replacing the "un-failed tire" because when it's "mate" failed the un-failed tire was overloaded by 100% for some unknown number of miles.
You can always take the un-failed tire to a dealer, for that brand of tire, and have it inspected inside & out, and if ruled OK, in writing, by the dealer, you could keep the tire as a spare.
However, if it ran some unknown number of miles at 100% overload, I would not even trust it as a spare.
Now in the case of a multi-axle RV trailer (tandem axle) and one tire failed and again you were not running a TPMS to get an advanced warning, we need to consider what happened to the load on that side of the trailer. Wouldn't all the load from that end of the axle with the failed tire transfer to the un-failed tire on that side of the trailer? This transfer would be transferred through the springs and the link between the axles. The load supported by the "failed" tire doesn't simply evaporate, does it? It has to be taken up by the un-failed tire on that side of the trailer.
So again that tire should be removed, inspected, and replaced as with the Motorhome example. It might be OK to keep as an emergency spare but only used with great caution and only if inspected and judged OK by a dealer of that brand of tire.
This is one of the things people do not think of when considering running TPMS. If you get advance warning of air loss in one tire in a "Dual" or "Tandem" location you not only might save the cost of the punctured tire if it was caught soon enough to be repaired but you might even have saved enough by not losing the 2nd tire not to mention avoiding the $Thousands of possible damage to the RV.