Badtoytrd,
I built a low camper dolly so I could pop my camper open in my 8 foot tall garage. I made the frame out of doubled 2x4's (oriented 3-212" in the vertical) with cross bracing and plywood top and bottom. I attached 5" casters from Harbor Freight, each rated for 350 pounds, in four corners. This is about as low as I could make it. I would not go with a smaller diameter wheel unless you will only be using the casters on a smooth floor with no gaps or step downs (such as the typical step down from inside a garage to outside that is there to keep water out).
My dolly worked fine on the smooth garage floor. However, my driveway is made of textured pavers (to simulate stone) and after about three moves across the driveway the pavers not only ripped the polyurethone off of the wheels when they swiveled but also caused two of the plastic hubs to fail.
After doing a fair amount of searching online I called Caster City. The fellow I spoke with at Caster City explained a lot about the materials and choices after I explained to him the camper wight and surfaces the dolly (casters) would be used on.
He recommended I go with 500 pound capacity or greater casters with metal hubs and high quality poyurethane tires as well as large of diameter wheel as possible.
He also recommended getting swivel locks (not brakes) and I added them onto the two casters on one long end of the dolly. The swivel locks, as the name implies, lock the caster so it will not swivel which prevents "crabbing" and allows me to push it in one direction when moving it. They are easily engaged or disengaged by pressing or lifting a small tab with the toe of my shoe.
Unfortunately the smallest caster with the recommended capacity and tread material is 6" and now that I have solar panels on the top of the camper the whole stack up would be about about 2 inches too tall to fully pop the top. So I decided to go with 8" casters to make rolling the dolly with the camper on it easier for me to do alone.
I will figure out how to hold the top partially open when it is on the dolly in the garage (a couple of 2x4 frames or something - not sure yet).
I installed the new casters today and they are really STOUT compared to the old casters. I am certain they will be fine but have not put them to use yet (that will happen starting tomorrow).
I do heartily recommend Caster City and if you call and talk to them you may get a discount over the prices listed on the web just as I did.
http://www.castercity.com/contact.htm
BTW: My camper jacks are not long enough to raise the camper high enough so I can get it in the bed of my truck so I use 6x6 blocks under the feet of the four jacks.
When putting the camper on the dolly I have to first use the 6x6 blocks and lower the camper onto a pair of 8x8x4' long boards laying across the width of the dolly then remove the 6x6 blocks from under the camper jack feet, raise up the camper, remove the 8x8 boards and lower the camper onto the dolly.
I don't think longer camper jacks are a solution because they already start to feel a little unstable when I get them to full height when putting the camper on the truck.
One of these days I may engineer a steel framed lift/dolly assembly to make getting the camper on and off the truck easier. I have an idea sketched up but it needs some refinement and engineering before going foerward with it.
Hope that is of some help.
Craig
