I don't believe there is an RV-related subject that causes more arguments than RV weight, unless maybe it's the argument over trailer vs. 5th wheel vs. motor coach. Between the cryptic way that RV weight is reported by the manufacturers, the lack of clear standards by the DOT and the often deliberate misinformation spread by RV dealers; RV weight is confusing at best.
We recently purchased a new RV - a process that finally prompted me to attempt to fully understand this subject. The following is what I learned, and in my humble opinion, an authoritative explanation of what the truth really is.
Let's start with the 2 RV weight 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. The other sticker required by law is a tire capacities sticker. This is usually outside the RV, somewhere near the hitch on towable RV's. It can 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 tow able.
The RV weight sticker displays all of the most important weights as they apply for your RV. The information on this sticker has changed over the years, but it should contain at least some combination of the following:
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 in your owner's manual. It contains many of the same ratings as they apply to the tow vehicles only.
By this point I was already beginning to feel the effects of RV weight information overload. Did I really need to fully understand all these numbers as well as the mathematics involved? Was it possible to reduce this to a manageable level and make intelligent, informed decisions? I finally worked it out into a few basic formulas that allowed me to fully comprehend all the essential information. With that in hand, we were able to make an informed purchase for our new RV.
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 reduce the amount of fresh water in the tank. The gross weights are fixed however, and short of making major modifications to the RV, are absolute barriers.
In our case we had already decided on a large travel trailer for our new RV. I don't intend this article to be a debate in the age-old travel trailer vs. 5th wheel vs. coach argument. Suffice it to say we have very good reasons for choosing a travel trailer over the other classifications. With this is mind, let's look at the all-important gross weights.
Weighing your rig is easy and costs very little compared to the alternatives. Load your rig with everything you think is necessary, fill it with fuel and drive to your nearest truck stop with a scale. In order to get enough information to calculate all the primary weights, you'll need to get two weighings.
First, weigh the entire rig as being towed, or in the case of a coach with a chase car attached. Just make sure both your TV (Tow Vehicle) axles and the TT (Travel Trailer/5th Wheel) axle(s) are on 3 separate weighing pads.
That will give you weights for your steer axle, your drive axle and your TT or chase car axle(s). Next, take the TT or chase car and "drop" it in the parking area so you can come back and weigh just the TV or coach; again, making sure the steer axle and drive axle are on different pads to get 2 separate weights. From these 2 weighings you can calculate all the weights you need.
GCVW (Gross Combined Vehicle Weight) is the total weight of the first weighing. It is important that you do not exceed your TV's rating or your coach rating on this. If you do, you could find yourself facing that lawsuit for negligence I mentioned earlier, not to mention that fact that it's unsafe. Your coach or TV are only engineered to handle that much weight and you could face brake failure, tire failure or other issues if this weight is exceeded.
TV GVW (Tow Vehicle's Gross Vehicle Weight) is the total of the second weighing. Like the GCVW, it is important to not exceed your TV or coach's max rating.
Axle weights. Each of your TV's axles have a max rating, as does your TT. From the individual weights of the axles in both weighings you can tell if you're exceeding any of the max ratings for your axles. Pay particular attention to your TV's drive axle from the first weighing. It will be heavier than it is in the second weighing because of the tongue weight of the TT or chase car.
TT GVW (Trailer's Gross Vehicle Weight). For this one you need to do a bit of math, but it's not difficult.
TT GVW = GCVW - TV GVW
Both your TT and your hitch have a max rating for this. This weight must not exceed either the GVWR of the TT as found on the sticker, or the Max Towing Capacity of your TV. Hitches also have 2 max ratings, one for the max towing weight (this weight) and one for the weight of the trailer tongue.
Tongue Weight. For this one you need to do a bit of math as well:
Tongue Weight = GCVW - TV GVW - TT Axle Weight
This needs to be within the max tongue weight rating of your hitch.
One last thing ... Your tires on both your TV and TT. Many people overlook their tire load rating. The load rating is found on the tire sticker and written on the side of your tires and should not be exceeded.
Personally, I want plenty of safety margins here. If you run your tires close to their max load rating, it will wear the tires prematurely. More importantly, if you experience a blowout of one tire on a tandem axle, the other tires are now carrying considerably more weight than they are rated to carry: especially the ones on the same side as the blow out. It is possible to damage multiple tires in a situation like this before you can even get the rig stopped.
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 seemed easier for me to deal with the gross ratings and let the other level out as needed. Since we're full-timers that travel a lot, I weigh often. It will surprise you how much "cargo" you accumulate as time goes by.
It's easy to weigh at commercial truck stops and the cost is usually reasonable. Most truck stops will only charge you full price for the first weighing, then a small additional price for the second weighing. The last time I weighed at a CAT scale at a Love's truck stop, they charged me $7.00 for the initial weighing and only $1.00 for the second one. A small price to pay for peace of mind.
Phil & Karen King are full time RVers. They travel 12 months a year and have extensive RV'ing experience.