Going with larger wheels seems like it would not be a problem. Going smaller would increase the rotation at a particular speed and could reduce the life of the barings, but bigger -- OK.
</font><font color="blue" class="small">( Sorry, but big wheels can cause problems. These other guys simply are wrong about the issue of wheels. The earth, while spinning under the rotation of the larger diameter wheels will likely speed up if you travel with the earths rotation and will likely slow down if you change direction, thus creating an imbalance in the universe. I for one, would not mess with it. The consequences could be tragic. /forums/images/graemlins/wink.gif )</font>
So I understand the east-west travel problem you've described, but does this mean that if you go north, the trailer would flip over toward the west because of the right hand rule of the conservation of angular momentum? It's been a while since I studied trailer dynamics (modeled as a fluid, of course), but I think also that the rotation of the larger wheels could induce a current in the trailer frame causing static electricity buildup and eventually causing the paint to turn a unique shade of green, and eventually causing it to fly off and stick to your clothes.
Cliff