Motorhoming | Family Motor Coach Association
By Mark Polk
RV Education 101
It’s that time of year again — time to load the motorhome, hitch-up the towed vehicle and just RV it. It’s always exciting to hit the open road and see what adventures await.
If it has been awhile since you last prepped your motorhome for a road trip, I’d like to remind you of some motorhome weight issues that, when overlooked, can affect your RV travels.
1. We’ll start with one of my favorites, checking tire inflation pressure. When your RV sits in storage the tires lose inflation pressure each month. If proper tire pressure is not maintained, based on the load on a tire, it can result in fast tread wear, uneven wear, poor handling, and excessive heat buildup, which can lead to tire failure. Tire manufacturers publish load and inflation tables that should be followed for proper tire inflation pressure.
2. Do not exceed the gross vehicle weight rating (GVWR). This weight rating is one of the most crucial safety factors concerning your motorhome. The GVWR is the maximum allowable weight of the motorhome when it is fully loaded for travel. When you exceed the GVWR you risk component failure, which can result in an untimely breakdown or worse. The only way to know if you are exceeding any weight rating is to have the fully loaded motorhome weighed.
3. Do not exceed any gross axle weight rating (GAWR). The GAWR is the maximum allowable weight that can be loaded on an axle. The GAWR is based on the component with the lowest weight rating in the system. This could be a suspension component, brake component, wheels or the tires.
On motorhomes, it’s common to be within an axle weight rating, but for one end of the axle to still be overweight. When this happens there is a good possibility you are exceeding a tire weight rating or other component weight rating on the axle end that is overloaded.
When an axle end is overloaded it might be possible to redistribute some weight to correct the problem. To avoid an axle end being overloaded, even though the axle itself is within the specified weight rating, weigh the motorhome at scales where individual wheel positions can be weighed, too.
4. Do not exceed the hitch receiver weight rating. Your motorhome may have a tow rating of 5,000 pounds, but if the hitch receiver is only rated for 3,500, you cannot exceed the receiver’s rating. This was quite common on many older motorhomes.
To accommodate the length of the box being built on the vehicle frame, manufacturers add frame rail extensions. When these frame extensions are added it can limit the amount of weight the frame can support, so a hitch receiver with a lower weight rating is installed on the frame. This lower-rated hitch receiver is often overlooked and can result in towing and safety concerns. To solve this problem it’s important to check the hitch receiver’s tow rating prior to towing a dinghy.
5. Do not exceed the gross combined weight rating (GCWR). This rating also affects the total amount of weight you can tow or add to your motorhome. The GCWR is the maximum allowable combined weight of the fully loaded motorhome and the fully loaded vehicle/trailer that is towed behind the motorhome.
For the sake of a simple example, let’s say your motorhome has a GCWR of 26,000 pounds and a GVWR of 20,500 pounds. In this example the max dinghy or trailer weight you could tow behind the motorhome is 5,500 pounds. Keep in mind you can only tow this amount of weight if the hitch receiver is rated for the weight.
Another problem is lots of folks don’t realize how much their fully loaded dinghy actually weighs. Take the vehicle to the scales and have it weighed to make sure it can safely be towed by your motorhome.
Truth be told, many older motorhomes exceeded the GVWR when the motorhome was manufactured, before any additional weight or a dinghy was added to the equation. Again, you should weigh the motorhome to make sure you are within all weight ratings.
6. While we are on the topic of towing, the next weight consideration would be your tow bar and other components in the towing system. Every component in the system has a weight rating. This includes the tow bar, hitch ball, ball mount and safety cables. Your motorhome might be rated to tow 5,500 pounds, but if the tow bar (or other component) is rated for 5,000 pounds (or less), you cannot exceed that amount of weight.
7. Last on my list and perhaps the most controversial is the use of a supplemental braking system on the towed vehicle. In my humble opinion, the brakes on a motorhome are designed by the vehicle manufacturer to stop the weight of that particular vehicle, not the additional weight being towed behind it. This additional weight adds a substantial increase to the distance required to stop safely.
Some motorhome chassis warranties are voided if you tow amounts over 1,500 pounds (possibly less) without a supplemental braking system. When I am towing a 3,000-plus pound vehicle, I feel much better knowing I have a supplemental braking system on the towed vehicle.
Some of these weight issues are easy to overlook when we are getting ready for our next RV adventure. Of course, the only way to know if we are overweight is to take the fully loaded motorhome and towed vehicle to the scales and have them weighed.
To enhance our RV experiences and stay safe on the road, make a conscious effort to understand the weight issues we are confronted with. If you discover any overload conditions on your motorhome, resolve the issues immediately.
For more information and downloadable charts on how to weigh your RV, visit www.bridgestonetrucktires.com