Does this make any sence?

[KKELLER14K]

I'm throwing this out there for anyone who could explain this...why would a toy hauler have it's wheel base more in the middle of the frame where as most of the weight could or would be stored towards the rear of the RV? Semi truck trailers have their tire sets at the rear of the trailer(yes more tires) ... but WHY? Would it make sense that if you haul a heavier load in the rear that the tire set is closer to the rear to the overall load of the trailer? Why don't we use the dually tire sets on these bigger RV's?? Construction trailers use the dual tire concept am I missing something or stirring the pot?

[jmtandem]

as most of the weight could or would be stored towards the rear of the RV?

Think of it this way. An 18,000 pound gross weight toy hauler might have a 4000 pound payload. That means the hauler weighs 14,000 pounds without the toys. Consequently, the toys are really not that huge of a load compared to the total weight of the toy hauler. Putting the axles all the way to the rear would create an excessive pin weight even with the weight of the toys as there is still 14,000 pounds of hauler weight that has to be carried somewhere. And, for most it is carried on the haulers axles. A 20-25 percent pin weight allows for a one ton pickup to be able to tow the hauler as only about 3600-4000 pounds of all the 18,000 pounds is on the hitch.

[Old-Biscuit]

DutchmenSport wrote:

Old-Biscuit wrote:
Pin weight.........axle load ratings based on the fulcrum/lever principle
ie: F = (W x X)/L

That's a nice formula but what does f W X & L mean.

Fulcrum/lever equation

[DutchmenSport]

Old-Biscuit wrote:
Pin weight.........axle load ratings based on the fulcrum/lever principle
ie: F = (W x X)/L

That's a nice formula but what does f W X & L mean.

[Old-Biscuit]

Pin weight.........axle load ratings based on the fulcrum/lever principle
ie: F = (W x X)/L

[hone_eagle]

Marketing - keeps the pin weight down so they can sell you a "1/2 ton towable" rig.
Pick ups have a massive pulling ability but less (in proportion) weight carrying ability. a recipe for disaster if you are not careful, as on the bounce you can unload the rear tires enough lose traction or even contact (with the road) to jack knife .

[jmtandem]

I'm throwing this out there for anyone who could explain this...why would a toy hauler have it's wheel base more in the middle of the frame where as most of the weight could or would be stored towards the rear of the RV? Semi truck trailers have their tire sets at the rear of the trailer(yes more tires) ... but WHY? Would it make sense that if you haul a heavier load in the rear that the tire set is closer to the rear to the overall load of the trailer? Why don't we use the dually tire sets on these bigger RV's?? Construction trailers use the dual tire concept am I missing something or stirring the pot?

The pin weight would be much higher if the toy hauler's axles did not carry most of the load. Eighteen wheeler trailers that can weigh up to 50,000 pounds or so can slide the tandems (move the trailer's axles) to distribute the weight between the truck's axles and the trailer's axles. Toyhaulers typically do not have that provision. So, the manufacturer must place the axles where it has the best fit for carrying the weight for most circumstances. I am sure most toyhauler owners would not want around 6-9000 pounds on the pin if their hauler weighs 18,000 pounds because the toyhauler axles are as far in the rear as possible.

[DutchmenSport]

Every toy hauler I've looked at has the axles farther to the rear (5er and TT versions) opposed to their sister non-hauler (same length, brand, and manufacturer). Non-Haulers do have the axles forward more.

I'm sure every "hauler" comes with a weight limit for the garage area. This is to ensure the tongue weight does not decrease so much, the tail is too heavy, reducing weight on the hitch, causing bad towing conditions.

Move the axles farther back, and the hitch weight or tongue weight increases tremendously. It doesn't take much axle positioning to the rear to cause an excessive amount of hitch weight, that even a one ton would have problems with. So manufacturers have done the "math" to determine the best location for the axles with a recommended "do not exceed" wight for the garage to ensure good hitch weight and still be able to carry a load in the garage.

[stro1965]

I went from a 38' KZ 5th wheel to a 38' Keystone toyhauler. The axles are definitely further to the rear on the toyhauler.

[Lantley]

Moving the axles towards the rear increases the pin weight. This puts more weight on the truck which creates a different set of issues . It also changes the pivot point and maneuverability of the trailer.
18 wheelers are pulled by much larger trucks capable of towing 80K trailers. Totally different ball game than RV's.

[jerseyjim]

Y'think that's bad ? (Not necessarily so)...how about the incredible rear overhang on some of the larger Class C motorhomes?

[colliehauler]

All the TH'S I have purchased TT and 5th wheels had the wheels towards the back compared to a regular RV. The engineering department probably designed them for best balance for truck and trailer. TH'S already have a high pin weight and increased pin weight would require a med duty or OTR truck to pull it, like a semi.

Numar mountaineer use to use duel's on there big 5th wheels.

[tmm2good]

If you have no weight in the garage, would that not make the tongue/pin weight super heavy?

[KKELLER14K]

so moving the tire set back is detrimental how? I'm not understanding this at all. My thinking is that it could carry more load weight wise in the rear..

[Aridon]

Very likely that any added weight capacity would overwhelm the CCC of the unit or the frame would be out of balance / loaded in a bad way and you could have more failures.

They are balancing the capacity of the frame and the CCC of the unit with everything else on a giant sea saw that can have varied loads. The current placement is likely the safest and given the relatively low CCC of the units moving the wheels back further likely offers no benefit and perhaps could be detrimental.

Then again, maybe the guy that designed it is a jackass.