Calculating actual 5th wheel weight being put on hitch?

[Radioherd]

Hey All,

We jumped on the cat scales yesterday and got the following readings:

Steer Axle: 5380
Drive Axle: 7460
Trailer Axle: 12760
Gross Weight: 25600

What i really need to know is how much weight is my hitch actually dealing with - i know its not as simple as adding the drive axle to the trailer axle (as that would include some weight from the back of the truck), so how do you actually calculate the weight of the 5th wheel only? Do you have to disconnect on the weigh scales?

 

[Lou Schneider]

You'll have to run your truck alone over the scale again to get it's unloaded weight. Subtract this weight from what you got with the trailer attached to find the trailer's hitch weight - how much weight the trailer is putting on the truck. This plus the weight on the trailer axles gives you the total trailer weight.

Don't unhitch while you're on the scale. Pull off, unhitch and make another pass. At most scales the second pass (called a re-weigh) is free. Truckers do this all the time if they have to adjust their load to be within legal limits.

 

[Onyrlef]

You'll have to run your truck alone over the scale again to get it's unloaded weight. Subtract this weight from what you got with the trailer attached to find the trailer's hitch weight - how much weight the trailer is putting on the truck. This plus the weight on the trailer axles gives you the total trailer weight.

Don't unhitch while you're on the scale. Pull off, unhitch and make another pass. At most scales the second pass (called a re-weigh) is free. Truckers do this all the time if they have to adjust their load to be within legal limits.

As I recall Cat Scales will charge for the second pass for RV'ers but it's about half the initial weigh. When I was towing a TT I'd make multiple passes to determine tongue weight and WDH affect on axle weights.

 

[Rene T]

Here’s The way I did it. I drive up on the scale just far enough so that the truck only is on the scale and the front landing gear will be off the scale. Take a reading. Then lower the landing gear so that the trailer is off the hitch then take another reading. Subtract the two for your hitch weight. Then lower the trailer back on the hitch. Then pull the truck forward far enough so that it’s off the scale and take another reading . Add this reading with the hitch weight reading and you’ll have the gross weight of the trailer.
It’s basically the same process Lou said.
Note: every reading I took I got out of the truck and stepped off the scale.

 

[Onyrlef]

Here’s The way I did it. I drive up on the scale just far enough so that the truck only is on the scale and the front landing gear will be off the scale. Take a reading. Then lower the landing gear so that the trailer is off the hitch then take another reading. Subtract the two for your hitch weight. Then lower the trailer back on the hitch. Then pull the truck forward far enough so that it’s off the scale and take another reading . Add this reading with the hitch weight reading and you’ll have the gross weight of the trailer.
It’s basically the same process Lou said.
Note: every reading I took I got out of the truck and stepped off the scale.

That probably won't get you nominated "most popular" in the Truck Stop Yearbook.

 

[Rene T]

That probably won't get you nominated "most popular" in the Truck Stop Yearbook.

Why, it would only take no more than 5/10 minutes. No need to totally disconnect

 

[Tulecreeper]

Why, it would only take no more than 5/10 minutes. No need to totally disconnect

True, but those guys are usually in a hurry to get back on the road. I found that just stopping and asking the weigh master what time of day is least busy works better...for them and for me. I'm not holding anyone up, so I can take my time and not feel rushed.

 

[Radioherd]

Ok thanks all - we are at 16480lbs

The GVWR of our rig is 16,995lbs - so basically we have just over 500lbs before we are at our safe limit yes?

 

[Onyrlef]

Ok thanks all - we are at 16480lbs

The GVWR of our rig is 16,995lbs - so basically we have just over 500lbs before we are at our safe limit yes?

Fiver hitch weights range a bit higher than bumper pulls, yours is actually low. most are in the ~15-20%+ of gvw

 

[Gary RV_Wizard]

Ok thanks all - we are at 16480lbs

The GVWR of our rig is 16,995lbs - so basically we have just over 500lbs before we are at our safe limit yes?

Yes, as far as total gross weight is concerned.

The hitch pin weight on a fifth wheel needs to be at least 20% of actual gross weight and 20-25% is common. Use 20% of the trailer GVWR as your target pin weight and you won't go wrong.