Hey all, I'm new to the group, thanks for letting me in!
We live in middle Tennessee and own a 1960 Metzendorf with a 10 foot body. Originally bought from friends of ours in New York about four year ago, we've had her from Canada to Key West, and getting ready to head to Portland Oregon in her this week. We've put thousands of miles of fun on her....
As for tires, the proper size now would be 195/75R15, but they quit making that size tire a few years ago. I do have 205/75R15's on ours, BUT, you have to let the air out to get the tire on and off. It's a pain, but I haven't found a solution yet, the 205's are just a bit too wide.
This chart from Tire Rack shows the conversion for earlier tires ...
https://www.tirerack.com/tires/tiretech/45_conversionchart.jsp