Merrbarb

I am a new member and the question I have may be for another forum: Where can I get tires and hub caps for these wheels? The all-steel spoke wheels are off a 1936 Travelcar house trailer but most surely were from an auto of that era since travel trailers were very scarce. It is a five (5) lug wheel. The tires that were on the wheels were 5.25/5.50/17. The inscription on the inside rim of the wheel is 17 over 3.25, and another inscription is: MF'R'D BY Motor Wheel Corp. xxxxx MICH USA. Are there tires made especially for trailers of that era, or just for autos? I appreciate your help, and thanks.