On small single axle trailers I use a P tire as they have plenty of capacity and will handle any speed and years of service.
A neighbor pulls his wifes 1500 Ram 4x4 off road truck on a dolly behind his MH. He bought the dolly used and up graded to 15" P tires and wheels.
"good judgment comes from experience, and a lot of that comes from bad judgment" ............ Will Rogers
'03 2500 QC Dodge/Cummins HO 3.73 6 speed manual Jacobs Westach
'97 Park Avanue 28' 5er 11200 two slides