Today we ordered the fabrication of our custom tiny house trailer- big step, and it took a lot of sweat and time to get here. The process is like anything- the more you know, the more you realize you don't know, and it just gets more sweaty and time-intensive as you go. Here's what we learned about how to place the axles for your custom tiny house trailer:
- Know how the balance should work on a tiny house. Because you're not building it to sit still, the balance should not be in perfect equilibrium. You don't want to let go of the front of the trailer and have it remain upright and balanced; generally you'll want 10% of the total weight to be resting on the tongue. This means if our tiny house is 10,000 lbs, the tongue will weigh 1,000 lbs. You will not be picking that up.
You don't want the trailer pulling up on the back of your tow vehicle, and when you get it moving, the momentum will do weird things to the trailer's behavior if it has a shed roof front-to-back like ours. The wind is going to want to push down on the back of the trailer to flatten out the plane (we have not hired an aerodynamics engineer to find out how much, but we believe it's not substantial).
There's a great article on managing tiny house towing weights here.
- Know where your trailer fabricator likes to put the axles as a default. It's interesting- the two main trailer fabricators, Tumbleweed and Tiny Home Builders, put their axles at slightly different points along the length of the tiny house trailer as a default. Tumbleweed puts the center of axles 55% of the way back, and Tiny Home Builders puts theirs 58% back (both of these are measured from the front of the trailer bed, not the tip of the tongue). Either of these are approximately correct enough for most tiny house people, but if you want to use a more accurate engineering approach, then read on...
- Know how much your tiny house will weigh. This is very challenging. You need to account for every stud, joist, insulation unit, fixture, piece of heating/cooling equipment, furniture, etc, etc. We did this by building a 3D computer model of our Tiny Lab and creating an inventory from there in a spreadsheet. Our engineer buddy John Bergman then figured out where the center of gravity was in the X, Y, and Z axes (vertically, front to back, and left to right). The Tiny Lab is estimated to be 9,300 lbs, with the center of gravity right down the middle, and 45% of the way back.
- Split your axles over the point 10% of the way further back. Our axles are located 55% of the way back, which Dan Louche at Tiny Home Builders was easily able to include in our trailer design. Stay tuned for all the videos of the construction process, which starts in under a month!