I'm more of a Reader than a Searcher but this has come up before. I haven't tried this swap on a Chevy, but my recall (so be careful with what I say) is that the GM units are an easy swap. Your coach might have come with 8.00/16.5 or more likely 8.75R16.5D
The 245R16 is way more tire than the GVWR of a Class C that age calls for. You can find plenty of charts that address the Diameter, Width, Rim Width, and Load Rating. Were I doing it, I'd be looking for the 16" that comes closest to 8.75R16.5D which I heard (but haven't confirmed myself) is the 225R16. That one's available in D or E, but I think most are sold as E, even though that's only required on 450/4500 series Class C.
Problem with that is the popular donor trucks you'll probably look for (dually pickups) might carry a different size than that. You'll have to check charts to see how much the size changes the dimensions, then make sure you have wheel clearance all around, and steering clearance in front. Tire shop should be able to tell you which sizes they sell most for what.
