Generally owners increase Load Range on tires from C to D or from D to E...
this gives a little more stability and toughness on sometimes rough roads...
while increasing tire SIZE (diameter or width) is sometimes not doable due to dual axles being too close together or the decreased clearance of trailer chassis to tire height or width causing tires to rub on the wheel well or suspension parts...
Sometimes owners do a makeover of the suspension and tires to give increased ground clearance if they do a lot of "boon-docking" over rough unpaved roads.