Axles and GVWR do not match up.....?

[Parks]

So, in my search I have noticed that many of the manufactures have their axles not matching up to the GVWR of their trailers/5ers weights. I see lots of 5ers and TT with GVWRs in the 15K-16K pound range but are only sporting two 6K axles. I see units with axel capacities pushing 2500+ lbs less than the units GVWR.

Why is this? What about potential failure? Would seem better to have the axle capacity to at least match the GVWR of the unit.

[Mich F]

You're forgetting the hitch/tongue weight. That will be between 10 and 20 or so percent of the trailer/5th wheel weight. The axles don't have to support that weight.

[V3600]

Because the tow vehicle carries some of the weight. Fifth wheel: There might be 2,000 pounds or more, for example, of pin weight on the hitch in the bed of the truck. Subtract that weight from the GVWR and leaves the weight on the axles themselves.

[Cat320]

Normally about 20% of a 5th wheel's GW is carried in the truck as pin weight.

[FastEagle]

Calculating the weight and balance for RV trailers is a little different because the axles are never going to carry the full weight of the trailer. When setting by itself the unit is kept level - fore and aft - by it’s landing gear. When being moved from place to place some of that landing gear load is carried by the tow vehicle.

Before the RV trailer leaves the factory some of its safety equipment must be certified. That includes its total weight (GVWR) all axle weights (GAWR) and its cargo load capacity. The GVWR is the build target. After the GAWR values are set and a hitch weight has been determined the cargo capacity is determined. By regulations, the total GAWR, when added to the established hitch weight, must equal or exceed the GVWR. Once delivered to the middleman/dealer, adjustments may be required in the cargo capacity if options exceeding xxx weight are installed by the dealer.

The manufacturer’s established hitch weight is an ideal figure. After the vehicle is sold that ideal figure is controlled by the owner, as is all other weights and the balance of the unit.

This is an excerpt from a NHTSA Q&A pdf.:

"The FMVSS have requirements for the manufacturer to use proper tires and rims for the gross axle weight rating (GAWR). The manufacturer may determine the GVWR by adding cargo capacity (if any) to the curb weight of the vehicle as manufactured. The wise consumer, before purchase, will determine if the vehicle has sufficient cargo capacity to carry the weight of water, additional equipment (such as televisions, and microwave ovens), and luggage. The manufacturer’s certification label must show the GVWR. The GVWR must not be exceeded by overloading the vehicle. There is little the government can do to assist a consumer who has purchased a vehicle that has insufficient cargo capacity for its intended use."