Axle math question

Pin weight.

6,000 + 6,000 = `12,000. If the GVWR of the FW is 13,500#, the pin weight is probably around 20%, or 2,700#

So add the 12,000 plus 2,700, and you have 14,700. This is more than enough to safely handle the FW. On my rig, the GVWR is 13,995 (with two 6K axles), and I still have plenty of reserve capacity based upon my pin weight.

Jim

2oldman wrote:
Pin weight.

OK, thanks. Travel trailer math was much easier.

ky-auctioneer wrote:

2oldman wrote:
Pin weight.

OK, thanks. Travel trailer math was much easier.

Always thought TT was more involved then FW

FW......once across scale without FW then once across scale with FW.
Difference in Trucks Rear Axle weight....FW pin weight (might check if front weight changed)

TT.....once across without TT, then once across scale with TT but WDH not connected, then once more across scales with WDH hooked up. Then weight before, weight after, weight with, weight without, ride height with, ride height w/o...............:B

Even a 11,000 GVWR Trailer might have a pair of 5,000 or 5,500 pound trailer axles, and rely on the 1,000 - 1,200 pounds of hitch weight.

I wonder why the salesman did not know this already. If he had even looked at one of the brochures (they usually are sitting around waiting for customers to show up, so should have plenty of spare time to read one a day, in a week they should understand each of their products), it will list the axle weight ratings, and pin weights empty. Anyone with basic math can tell after reading a bit that the GVWR is a combination of what is on the axles and pin.

So the trailer in question, might have 2,500 on the pin, and the remaining on the axles, or about 5,500 per axle. This can vary from one axle to the other and side to side. Say the slide out is drivers side. You might have 2,900 on the drivers side tires, while only 2,400 on the passenger side. This will still not axced the tire weight rating (hopefully), but it could. This is why filling the fresh water tank, and taking it to a scale where you can get side to side weight and each axle is important.


Also bewary of the fact that a GM dealership will sell you a Duramax and say 'it will tow anything'. While it might tow any 10,000 pound trailer fine, it will not tow a fifth wheel if it can only handle 2,000 pounds of cargo.

You would need a 3500 series truck, with sufficient cargo rating to handle a 13,500 GVWR fifth wheel. Not every 3500 truck will do it. A gas model, that is not a heavy crewcab, and not with the 4X4 400 pound option might work well with the 2,700 pound hitch pin weight, 150 pound hitch, some firewood in the bed, perhaps a generator, and still have cargo capacity left over for passengers and other stuff in the truck.

Many owners of 2500 pickups ask 'how can I tow a fifth wheel, the GM dealer said it will tow anything, but it only has a 1972 pound cargo rating, and my family of 5 weight is 800 pounds, leaving just 1,172 pounds for the trailer hitch!

The common reply is do not buy a 2500 for fifth wheel or camper use.

Good luck,

Fred.

GCWR

sail2liv wrote:
GCWR

For pin weight :H

Pin weight, the only thing a salesman knows or is concerned about is his commission.

This is called: designing it for 'just enough'...not a whole lot of safety margin here

There are 7K GAWR axles out there...assuming they cost more than 6K GAWR axles...

Trailer OEMs are notorious for going 'just enough' on their designs...