16 inch tires offer the most options for LT tires
LT 265/75R16E are rated for 3415 pounds
LT 245/75R16E are rated for 3042 #
LT 235/85R16E are rated for 3042#
there are 100's of tires available in each of those sizes
the best bet is to find a 16 inch steel wheel that will fit your trailer.
the least expensive method of doing this is to replace the brake drum assembly with a 6 bolt pattern drum to attach a steel wheel.
tire diameters and widths are listed on the tire rack website .
a tape rule will help you decide if you have adequate clearance without raising your trailer.
the 245/75R16E is most likely to work within your wheel well .