What if I told you that you were probably doing it wrong, and in fact, driving your rig might actually be an accident waiting to happen? Yeah, I know, you have spent hours on YouTube and Facebook boning up on how to RV, but the least discussed topic I have found is four corner weights! Have YOU heard of it? Do YOU do it?
Understanding the weight labels on your RV
Let’s take a minute to discuss the vehicle weight charts you’ll find, usually inside one of your overhead cabinets. Here is an example of a very popular 31′, Ford, V-10 motorhome. When most people look at this they see a total weight of 20,500 lbs. Others see what are called axle weights, or 7000 lb steer or front axle, and a 13,500 lb rear or drive.
Over 90% of all RVers think the two weights circled in RED are all that matters; this is incorrect!
The fact of the matter is these numbers have to be divided by TWO! You have TWO wheels each sharing the gross axle weight!
So what is the solution? The answer is very simple, weigh your coach! But first, let’s go ahead and look at another sticker before we actually get to the proper way to weigh your coach!
As you can see from the tag above, this coach is able to carry up to 4,901 lbs of cargo. The weight of the coach, its accessories, full gas, coolant, oil, water and LP tanks and two people are already factored into the weight. Did you notice anything missing from this tag? You got it! Waste water tanks! Make it a habit to DUMP your tanks before you travel!
Full waste tanks can add anywhere from 800 to 2000 lbs to your gross weight!
So now that we have a good understanding of weights, axle weights and cargo weight, let’s use a real life example:
Using the second label as an example, this coach has a gross vehicle weight of 31,000 lbs.
The front gross axle weight is 10,400 lbs, The rear gross axle weight is 20,600 lbs.
So from what we have learned so far:
EACH front wheel can support 5,200 lbs. maximum, independently.
EACH double rear wheel can support 10,300 lbs. maximum, independently.
(NOTE: This example is of an RV with a tag or third axle, hence the rear can be over the 20,000 lb DOT limit)
Four Corner Weights – How To
- The first step in proper weighing of your coach is to make sure it is fully loaded out as it would be for your trip. This includes a full tank of gas, and however much water you’re going to carry in the freshwater tank. I usually only travel with 10 or 15 gallons of fresh water.
- Next find a Cat Scale. Most major truck stops have Cat Scales. Here is a link to the Scale finder website. Links to the App are at the bottom. The scale you use for this should be FLAT and have open sides.
- Position your rig on the scale using the diagram and photo below as a reference. Note that ONE COMPLETE SIDE of your rig should be OFF the scale! Also note that the scale is divided into either three or four sections. These are individual scales, and will weigh each axle separately. See the diagram below the photo for more configurations.
4. There will be a yellow call box on the front of the scale. Press the button to ring the scalemaster. They will ask if this is your first weigh or a reweigh. You answer first weigh. They will ask for your company name. Tell them you are a private RV and give them your name and they will tell you to come inside to the fuel desk to get your ticket.
5. Park your RV off the scale in a parking spot and go inside to pay for your ticket. Cat Scales will typically charge between $10 and $13 for a first weigh and about $6 for a second weigh. If you have a rewards card with the truck stop, points can be used toward scale charges.
6. Return to your RV and drive back on the scale on the other side, with the opposite side off the scale. Press the button again and tell them it’s a reweigh of the private RV.
7. Park your RV again and go inside and purchase the reweigh ticket.
Calculating Four Corner Weight
So now you have the hard part done! Congratulations! You have taken your first step to being a responsible RV driver!
So now using the same example we used earlier, your tickets will have a printout of the two or more axle weights — in this example, just the two. Your front axle, according to your weight chart should be no more than 5,200 lbs on BOTH tickets, and your rear should be no more than 10,300 lbs on BOTH tickets.
In real life, your weight is NOT going to be evenly distributed! And in fact, most RVers will be surprised to find that there will be at least one wheel that is overloaded and unsafe to drive on! It is estimated that more than 90% of RVs on the road at any given moment are over wheel weight on at least one wheel! This fact accounts for all the blowout horror stories we’re constantly seeing on Facebook and in the news! I want you to watch the complaints on the Facebook groups carefully… notice that the people screaming China Bombs only have problems on ONE SIDE? Makes you think…
So, now with the same example, let’s say you get a weight of 10,600 lbs on the left rear and 9,450 on the right, what do you do? Well, you’re going to have to redistribute the weight from the left side of the coach to the right. In this case, you are under the maximum weight for the axle, but over the corner or wheel weight, and you would need to move 300 lbs. of cargo from the left side to the right. After you have moved the cargo, you have to reweigh the left side only.
The rule of thumb is, If the weight of one side of an axle exceeds the weight on the other side of that same axle by more than 5% of the total axle rating (GAWR), it is necessary to redistribute the load appropriately, but you can NEVER be over wheel weight! The number one cause of blowouts on RVs today is an overloaded wheel!
I sincerely hope you take this article to heart! I can tell you that if you do, your chances of getting a blowout on the highway will be significantly reduced! It truly breaks my heart to see all the posts on the Internet of RV accidents and rollovers! Many of them preventable with just a simple weighing. For less than $20 and a half hour of your time, you can confidently cruise the American highways without having to worry about a blowout from overloading… How much is your life worth?
Please note: Cat scales has a policy against four corner weighing and does not allow it. Individual stores may allow this practice and I have never been turned away, but I also don’t ask.
Now that you know how to properly weigh your rig before a trip, please take a few minutes to learn how to do a proper pre-trip inspection! Follow this link to learn how!
PLEASE ASK ANY QUESTIONS OR MAKE A COMMENT! I LOOK FORWARD TO HEARING FROM YOU!
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