When it comes to choosing a rim for a trailer tire, you will want to go with the smallest rim width available for your size of tire to keep the side walls as straight as possible. A 205/75R14 trailer tire like the Kenda, # AM20304, does fit a 5", 5-1/2", 6", or 6-1/2" rim so you would be good to go with this combination.
If you are looking for a wheel and tire combination, the Kenda Karrier ST205/75R14 Radial Trailer Tire with 14" Black Mod Wheel - 5 on 4-1/2 # AM32131 is another option... view full answer...