How To Weigh Your Recreation Vehicle
The first time to weigh your RV is even before you finalize the purchase. That way you can determine whether the vehicle will meet your needs in terms of carrying capacity. This is particularly important if you are purchasing a used unit, as you do not know what the previous owner may have added that will decrease your carrying capacity.
Weigh before you pay:
When purchasing an RV, you may not find a place to weigh wheel by wheel, as the RV Safety & Education Foundation strongly recommends. However, you can weigh each axle. Then, you can evaluate the placement of storage areas, liquid tanks, major appliances, slideouts, generator, LP-gas tank, etc. to see whether the distribution of these heavy components could cause problems. If the capacity is not reasonably distributed, you may have difficulty loading the coach within its limits.
When buying or weighing a coach, you must have a good knowledge of your personal weight carrying requirements. To help in your calculations, here are the approximate weights (pounds per gallon) of the liquids RV’s can carry: water — 8.3; gasoline — 6; diesel fuel — 6.6; propane — 4.5.
When determining your requirements, keep in mind that everything you put in the RV has weight. We know from our weighing program that the average couple carries approximately 2,400 pounds of “stuff,” and many full-timing couples may carry as much as 3,500 pounds.
Weighing your RV is critical to ensuring that no ratings / limitations are exceeded.
For a better understanding of RV weight definitions and terms please refer to: ‘Understanding RV Weights’ at www.rvsafety.com.
Weighing by wheel position:
Ideally, you will weigh it by individual wheel position. Considering the multitude of floor plans, slide outs, generators, holding tanks and the location of storage space available, RVs are frequently biased to one corner or one axle.
If you weigh your RV on a truck scale by axle and find that the vehicle is within GVWR, it could be that the vehicle exceeds a tire rating, especially if the GAWR is equal to the sum of the tire ratings, which is frequently the case.
Using a certified scale:
Test done by the federal government as well as several independent sources indicate the only way to properly weigh an RV to establish tire inflation pressures as well as overloads is by individual wheel position weighing. Information obtained from truck scales designed to weigh by axle and up to 80,000 pounds do not give consistently accurate wheel position information for RV use. With the natural imbalance of a house on wheels (your RV) wheel position weighing is critical. To establish the initial weight of your RV when wheel by wheel weighing is not available, we suggest you use a certified scale. “Certified” means that a qualifying agency inspects the scale periodically to verify its accuracy. Most truck stop scales are certified, as are most grain elevators, co-ops, and other scales used in various trades. Please keep in mind you cannot accurately set RV tire pressure with axle loads measurements.
Determining the loads:
When weighing an RV, first determine the individual wheel loads, and then calculate the axle loads and the actual gross vehicle weight. Add the wheel loads for each axle and compare the total to the GAWR for that axle. If the total is greater than the GAWR, then you exceed this rating. Please refer to ‘Understanding RV Weights’ @ www.rvsafety.com for additional information.
Now, add all of the wheel loads together and compare that total to the GVWR for your unit. If the total exceeds the GVWR, then you exceed that rating.
Be sure to compare your wheel loads to the ratings of your tires. Remember that tire ratings vary with inflation pressure. If you discover a tire overload, resolve it immediately. Knowledge of tire load and inflation ratings can improve tire performance — and prevent accidents.
For more information on ‘Tire Ratings’ please refer to: ‘Tire load and Inflation Ratings’ at www.rvsafety.com
Towed vehicle weight:
If you tow a vehicle behind your motorhome, determine its weight and compare it to the tow rating of your hitch system. Also, compare the total weight of your motorhome and towed vehicle to the GCWR for your coach.
The same holds true for Tow vehicles towing Travel Trailers and 5th Wheels.
Know all your wheel position, axle and hitch loads, calculate total weights; compare these to GVWR, GAWR and GCWR.
If you tow a trailer or another vehicle that imparts vertical load to your hitch, you will want to verify that this hitch load does not exceed the vertical load rating of your hitch.
Also, keep in mind that many state laws and chassis manufacturers specify that if a vehicle exceeding a certain weight is to be towed, supplemental braking for the towed vehicle is required; so, check with the chassis manufacturer and obey all applicable state laws. The RV Safety & Education Foundation recommends: If it has wheels on the ground it should have brakes’.
This information was provided by f the RV Safety & Education Foundation. The Foundation sponsors RV safety programs and conducts educational seminars.