Changing a single axle tire

The easiest for you would be a bottle jack. It takes up very little room but I'd also carry a chunk of 2x8 to set it on so it doesn't sink into the ground. A chunk of 4x4 might also be necessary depending on how high your trailer sits. For myself, though, I carry a 1-1/2 ton aluminum floor jack from Harbor Freight so I don't have to kneel on the ground. I need a little chunk of 2x4 because my siding is right up against my frame and is a little lower so I need to space down from the frame. A fairly large cross wrench is nice for dealing with the lug nuts (be sure they have been torqued properly or they can be a bear to get off). Have the tire store balance and install the tires on the axle and watch for the torque wrench to be used. The torque wrench should be used for the final tightening - if it just clicks off without having turned the lug nut any, they have already over-tightened the lug nuts.