Perhaps there is no Tiny House subject (or trailer subject, in general) that causes more arguments and confusion than that of weight. Between the cryptic way that RV weights are reported by the manufacturers, the lack of clear standards by the DOT and the often deliberate misinformation spread by dealers; trailer weights are confusing at best. Because of our recent trailer purchase I have been motivated to try and really understand this often mystifying issue. The following is what I learned, and in my humble opinion, an authoritative explanation of what the truth really is.
Now, our trailer got its beginning as an RV, of sorts. So much of my research has a travel trailer/RV bend to it. If you purchase a trailer from a specific trailer/hauler dealer they should be able to give you specific weights for the axels, trailer, tongue, and hitch. If not, immediately turn around and go see someone else. For our purposes though, I am going to walk you through our process (and one that is becoming more popular with each small home.)
Let’s start with the 2 stickers that are required by law on every RV sold in America. The RV manufacturer is required to include a Weight Sticker on the RV that details all the important weight ratings and maximums. This sticker is usually located on the inside of one of the kitchen cabinet doors. If your trailer has no camper portion (let alone cabinets or cabinet doors) you can simply forego this step and hope the other steps lead you to the same result.
The other sticker required by law is a tire capacities sticker. This is usually outside the RV, somewhere near the hitch (as ours was) on towables. It can also be on the inside door frame, near the engine compartment or on the inside of the service door for motor coaches. In addition to these 2 stickers on the RV, you’ll also need the ratings from your tow vehicle if working with a towable. Now here is where it gets rather tricky. The acronyms.
The RV’s weight sticker displays all of the most important weights as they apply for your RV. The information on this sticker has changes over the years, but it should contain at least some combination of the following:
- GAWR (Gross Axle Weight Rating). The maximum gross weight that the axles will carry. This is independent of the weight rating of the tires.
- GVWR (Gross Vehicle Weight Rating). The maximum weight that the axles and/or the tires will carry. It is the lesser of the axle carrying capacity or the tire carrying capacity
- UVW (Unloaded Vehicle Weight). The total weight of an RV as it was delivered to the dealer. It does not include any dealer installed accessories.
- NCC (Net Carrying Capacity). This is the actual amount of cargo allowed. It is in simplest terms, GVWR – UVW = NCC. This is sometimes listed as CCC (Cargo Carrying Capacity).
- GCWR (Gross Combined Weight Rating). This is the maximum weight of this RV plus any towed vehicle combined. This is listed on the RV for motor coaches, but not towables. For towables you can get this rating from the sticker on your tow vehicle.
- Hitch Weight. The maximum weight the hitch can support. In the case of a towable this is the maximum weight the RV’s hitch can support and has nothing to do with the hitch rating of the tow vehicle. In the case of a motor coach this is the hitch rating of the hitch used for towing a chase vehicle.
- GVW (Gross Vehicle Weight). See GVWR
- CCC (Cargo Carrying Capacity). See NCC
- Gross Dry Weight. See UVW
- Dry Axle Weight. The weight of the trailer when the RV is on the hitch. This can be calculated as UVW – Hitch Weight = Dry Axle Weight.
All of these may not be on your sticker since some only apply to certain RV classifications. In addition, there may be other weights listed. In addition to the RV’s sticker, you’ll need to understand the weight rating of your tires. For towables you’ll also need to get the ratings from your tow vehicle. This sticker is usually found on the door frame of the driver door, or can be located in your owner’s manual. It contains many of the same ratings as they apply to the tow vehicle only.
By this point I was already beginning to feel the effects of information overload. Did I really need to fully understand all of these numbers as well as the mathematics involved? Was it possible to reduce this down to a manageable level and make intelligent, informed decisions? I finally worked it out to a few basic formulas that allowed me to fully comprehend all the important information.
Let’s start with the gross weights since these are ratings that are difficult to modify. It’s easy to adjust the amount of cargo you’re carrying or the weight of your Tiny House building materials. The gross weights are fixed however, and short of making major modifications to your design, are absolute barriers.
The most important weights to anyone considering a Tiny House are:
- GVWR of the trailer, the
- GAWR of the trailer, the
- Hitch Weight of the trailer, the
- Hitch Rating of the tow vehicle, the
- Load Ratings of all our tires and the
- GCWR of the entire rig as noted on our tow vehicle’s sticker.
These are the ratings that cannot be negated or exceeded regardless of the finished build or the contents of your house. There are very good engineering and legal reasons for not exceeding these ratings, no matter how you slice them.
If you pay the most attention to your gross weight ratings, the rest of the capacities seem to take care of themselves. Not that the others aren’t important, it just seems easier to deal with the gross ratings and let the other level out as needed.
Stay tuned for more weights such as vehicle weight, tongue weight, hitch weight, etc. For now though, my brain is fried. In the meantime, if you enjoyed this post or found it helpful consider sharing it on Facebook or Tweeting the link!