RV Sure LLC RV Sure LLC Watching your weight – A visit to a CAT Scale

Watching your weight – A visit to a CAT Scale

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Can I put more ‘stuff’ in the RV?

I recently took our RV to a CAT (Certified Automated Truck) Scale at the local Flying J Travel Center. We have been living in our 5th wheel trailer since July 2017 and although we still had a lot of unused space in the under-floor pass-through storage, I really didn’t know how heavy our loaded home-on-wheels was. Did I have any capacity available?

Before visiting the scale, I was able to prepare myself with information from manufacturer’s data stickers on my truck and RV, and their websites…..

Truck information

I drive a 2015 Ford F-350 DRW crew cab with a 6.7 turbo diesel V8 engine and 3.73 axle ratio. Using the 2015 Ford Towing Guide, I was able to determine that the maximum loaded 5th wheel that my truck can tow is 23,500 lbs. Also the Gross Combined Weight Rating (GCWR), the maximum for the combination of truck and 5th wheel trailer, is 32,100 lbs. Currently, Towing Guides for years 2003 to 2019 are available at the Ford Fleet Website.

Further information, pictured above, can be found on the data sticker located on the driver’s side door jamb of the truck. The important information here is the Gross Axle Weight  Rating (GAWR), which is 5940 lbs for the front axle and 9650 lbs for the rear axle, and the Gross Vehicle Weight Rating (GVWR) 14,000 lbs.

RV Information

Our RV is a 2017 Keystone Avalanche 365MB, information from the manufacturer’s brochure is shown below. Currently, Keystone’s archive has brochures available for model years 2001 to 2018.

This shows the shipping weight, or empty weight, to be 13,145 lbs, the carrying capacity is 2,355 lbs and the hitch weight, the weight of the king pin on the 5th wheel hitch in the truck bed, is 2,730 lbs.

Now let’s look at information on the manufacturer’s data plate, located at the driver’s side front of the RV….

This tells me the Gross Vehicle Weight Rating (GVWR) is 15,500 lbs, which matches the sum of the shipping weight and carrying capacity shown in the brochure.

Next is the Gross Axle Weight Rating (GAWR) at 7,000 lbs. I have two axles, so the maximum weight over them is 14,000 lbs.

Now things start to be a little different than the brochure…..

My cargo-carrying capacity is 903 KG (1,991 lbs) when the fresh water tanks are full, 204 KG (450 lbs) of cold and 45 KG (99 lbs). This gives a total of 2,540 lbs, not the 2,355 lbs shown in the brochure.

It is also interesting to note that I don’t have a 66 gallon fresh water holding tank as the brochure lead me to believe. Convert the pounds of water to gallons and you’ll find that the fresh water holding tank is 54 gallons, with the remaining 12 gallons being held in the water heater.

Also, if my waste tanks are full, at 500 KG (1,102 lbs) they would take up over half of the carrying capacity.

Just to confuse things a little more there is another sticker below the data plate which tells me cargo should not exceed 2,380 lbs. Let’s just say that carrying capacity is somewhere between 2,355 lbs and 2,540 lbs!!!

Off to the CAT Scale then….

Before visiting the CAT Scale I ensured that the fresh water holding tank and the waste water holding tanks were empty, the only water on board was the 12 gallons in the water heater. As we live in our RV it was fully loaded with essential possessions and food.

The scale is divided into 3 platforms, each one able to record a separate weight. To get the best information the RV is weighed twice, first attached to the truck and then alone.

The first weighing will provide the truck front axle weight (1), truck rear axle weight (2), and the RV’s combined axle weight (3). The sum of all is the total weight of the truck & RV combination.

Then after removing the truck, a second weighing provides weight on front hydraulic jacks (2), and the RV’s combined axle weight (3). This time the sum of the two weights is the total loaded weight of the RV.

On to the results….

Here is the weight sheet from pass one:

 

Ok, the truck’s front axle at 5,280 lbs is 660 lbs below it’s rating. This, to me, seems surprisingly close to it’s limit!

The truck’s rear axle weight at 7,620 lbs is a more comfortable 2,030 lbs below it’s rating.

The RV’s axles were carrying 11,840 lbs. As it has two 7,000 lb axles, this number is 2,160 lbs below their combined limit.

the gross weight 24,740 lbs is the total weight of the truck and RV combined.

Here is the weight sheet from pass two:

Let’s start off with the gross weight first. At 15,580 lbs it is 30 lbs over the GVWR for the RV, so I actually need to remove a small amount of weight to meet the limit.

If we subtract this gross weight from the previous gross weight we will get the weight of the truck alone. This comes to 9,160 lbs. Handy to know!

Notice that the RV’s axles are now carrying less weight than on the first pass? The front jacks are several feet back from the 5th wheel king pin so are now carrying some of the weight that was over the RV axles.

To calculate the king pin weight on the 5th wheel hitch in the truck bed we’ll subtract the RV’s axle weight of pass one from the gross weight of pass two. This gives us 3,740 lbs or about 24%.

This is above manufacturer’s estimates, usually 17% to 20% of the total RV weight, but is understandable since we have added a washer dryer combo up front, changed out the mattress for a residential king size, and I have tools including two 2,200 watt generators in the under floor storage.

I don’t think the items added would total the 1,010 lbs increase over manufacturer-stated pin weight, but they have undoubtedly moved the balance of the RV forward a little.

Now, if we add the king pin weight to the weight of the truck alone we get 12,900 lbs, just 1,100 lbs shy of the trucks GVWR. This calculation matches exactly with the sum of the truck axle weights from the first pass.

Final Thoughts

In visiting the CAT Scale I have determined that even though we have empty storage space, the RV is already loaded around GVWR. I will have to take things out before adding more ‘stuff’.

All axle loads are below their rated maximum, however the truck’s front axle load is a little closer to it’s GAWR than I would have liked.

Even though my truck is rated to tow up to 23,500 lb 5th wheel, I think it would be difficult to do so without overloading a truck axle, or exceeding the truck’s GVWR – at the lower estimate of pin weight (17%) there would be almost 4,000 lbs on the truck’s 5th wheel hitch.

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