"Split Rim wheels" -- These wheels should be avoided.
This scan from the 1949 Budd Wheel catalog illustrates the dangerous 2-piece "split rim" (also know as the "widow maker") is the Firestone Type RH-5.
The dominant feature of the RH-5 is the attachment of its halves near the wheel's center line. This connection point has an overlapping raised band around the inside of the wheel. This band will be seen on all types of RH-5 wheels, whether Budd style or traditional drop-center light-truck wheels.
These wheels can be hard to identify because you can’t really see how they are made while assembled. It’s easier to identify them by eliminating the other possible wheel types. They are not "Locking Ring," "2-Piece" or "3-Piece Wheels" because they don’t have an easily identifiable ring or rings on one side (lip) of the wheel.
They are not singe piece tubeless wheels because they do not have a dropped center (where the tire bead goes to allow you to work it over the rim for installation or removal). RH-5 wheels became popular in the late '40's (with manufacturers...) and were used extensively throughout the '50's and '60's.
They were last available from Budd in 1972 and from Kelsey-Hayes in 1976. Due to their design, they have not aged well.