This chrome hubcap has a great streamlined conical shape that was original to many 1960s travel trailers.
These fit in place by snapping around the outside of 3 or 4 nubs on the wheel. They do not fit on wheels with spring clips riveted to the face of the wheel.
Airstream used them on Caravels and a few other smaller trailers in the 1960s with 14" wheels. Shasta and other brands also used them. We are not aware of any 13" rims they would fit. They do not fit modern 5-bolt rims, but they do fit some old 14" 5-bolt rims.
Please take the time to verify the dimensions work on your rims.
IMPORTANT NOTE: One of the problems with the original and with this replacement is rust. We recommend spraying the chrome (and any other chrome on your trailer) with a clear lacquer (from the hardware store) before installing it. That will protect it from the salt and prolong its life.