Weigh To Go

If you’ve just purchased an RV, or if you’re researching to purchase one, you will probably have come across the subject of weights. There will be a lot of acronyms tossed about —things like OCCC and GCWR, as well as admonishments about traveling with an overweight RV. I remember being concerned about these things as a new RVer, because nobody had explained it to me, and I had no idea exactly how to determine if my RV was indeed overweight. 

But just because nobody explained it to me doesn’t mean these aren’t important concepts. They are. And the first thing I want to explain is why you should care. Basically, it all comes down to safety. 

Let’s Talk About Your Weight

Whether it’s a motorhome or a towable, your RV is designed to handle a certain weight. If you go over that weight, you’ll be operating outside what the engineers intended for your rig. Will the suspension be able to handle the weight, or will you wind up with a busted leaf or coil spring? Will you be able to motor over a mountain pass? Will the brakes be adequate to stop the rig in a safe distance on the other side? If your vehicle is under its weight limits, you can have some confidence in your answers to those important safety questions.

 

The weight limits you’ll need to be mindful of can be found on a sticker. On a motorhome or a tow vehicle, this sticker is typically inside the driver’s door on the door edge or door jamb but could be elsewhere in the rig. For a towable, you can often find the sticker on the side of the rig. Regardless of the type of rig, or where you find the sticker, there are some terms that you’ll find common to all of them.  

• GVWR: Gross Vehicle Weight Rating. This is the total allowable weight of the RV as you’re loaded and heading down the road. This includes not only the RV, but the people, cargo, water, and anything else you put inside it.
• GAWR: Gross Axle Weight Rating. The total weight is broken down further into limits for each axle. Each axle can safely support a certain weight. Because there can be some variation in how your RV is loaded, the sum of these axle weight ratings is typically more than the GVWR itself. That’s not a miscalculation because GVWR is determined by more than just axle capacities. You just need to make sure that you aren’t overweight on any of these numbers.
• GCWR: Gross Combined (or Combination) Weight Rating. If you’re towing, whether that’s a dinghy vehicle or a trailer of some kind, the weight of *everything* you’ve got hooked up and rolling cannot be more than this number. You won’t typically find this rating on a towable RV because it’s meant to be towed, not do the towing. But you will find this number on the vehicle you’ll be towing with. (i.e. your truck or SUV.) 

You may also see additional stickers with the term OCCC or Occupant and Cargo Carrying Capacity (or just “CCC” for a towable) on them. With these numbers, the RV manufacturer has done some preliminary math for you. Basically, they’ve weighed the RV, and they’re telling you how much available weight is left over for you and your stuff. They’ll also give you some hints as to what a full load of water and propane would weigh – since this should be deducted from your cargo weight. This OCCC figure also needs to consider the weight of any aftermarket accessories added by the RV dealer. 

These CCC numbers are useful for comparing different rigs and estimating how much stuff you can bring, but you don’t need to get too wrapped up around them. Because once you own the RV and weigh it properly, it’s that actual weight that really matters, and you just need to make sure it’s under the GVWR. At that point, these CCC numbers are just a mental yardstick. 

Under Pressure

Keeping your RV from being overweight is only one reason to properly weigh your rig. Another reason has to do with tire pressures and properly inflating your tires. Tires can safely support different loads depending on their inflation pressure, and tire manufacturers provide charts that list the pressures and carrying capacity of each time by size and tire type. A tire inflated to a higher pressure can support more weight.  

But inflating tires to their maximum pressures isn’t a great way to go about things. Tires are meant to absorb some of the shocks of the road. Overinflated tires will be stiffer and less flexible than normal, and this will lead to a harsher and less stable ride than properly inflated tires. (Granted, the ride quality is more of an issue for motorhome owners than towable owners because they ride in the RV.) Overinflated tires are also more susceptible to damage from potholes, curbs, or debris. 

On the flip side, you certainly don’t want to underinflate your tires. Underinflated tires will flex and heat up while driving, and this can lead to premature tire failure and blowouts. 

You can protect against both overinflating and underinflating your tires by simply knowing how much your rig weighs. Once you have the weight supported by each tire, it’s a simple matter to look up a load and inflation table for your brand of tires to determine the optimal pressure to run them at.  

Stepping on the Scale

An overweight RV or incorrect tire pressure, are easy enough troubles to avoid if you just know the weight of your RV. But knowing HOW to weigh your RV isn’t something anyone is born knowing how to do. And honestly, the first time you try it, you’ll get nervous. But don’t worry. It isn’t hard. You got this. 

The first step in properly weighing your RV, regardless of type, is to load it like you mean it. You need to head to the scales just as you would normally roll down the road. So if you normally bring a dog, load the dog. Mother-in-law? Bring her. If you normally travel with ham radio equipment, free-weights, a spinning wheel, kayak, dollhouses, pizza ovens, you name it… load it for your weigh-in. The best idea is to head to a weigh-in at the start of a trip, when you’re all loaded up, full of fuel and propane, and haven’t eaten through your supplies yet. 

And don’t forget the big-ticket items – your holding tanks. If you never use them, that’s fine. But we do, so I always head to the scale with a full tank of freshwater. At more than eight pounds per gallon, water is probably the heaviest thing you’ll load into your RV. And if I’m looking for a real “worst case” weight, I fill the waste tanks as well. (I’ll leave it to your imagination as to how to fill them, but freshwater also works for weighing purposes.) Now, we NEVER travel with full fresh, grey, and black tanks. But there is a possibility that we could, so for a true worst-case weight, I’ll fill them. (I empty the grey and black tanks immediately after weighing.) 

So you’ve got the RV loaded for a trip, and your holding tanks are full. Next, you need to find a scale. The most reliable place to find scales capable of weighing your RV is at a truck stop. I’ve heard that grain elevators, gravel yards, recycling centers or even garbage dumps may have scales you could try, but I’ve never been able to reliably locate any of those the way I can a truck stop with a CAT scale. 

Heading to a truck stop and mixing it up with the professional drivers and the big rigs can be more than a little intimidating. But they don’t bite (usually), and the procedure to get the weight is simple enough.  

These days, if you have a smartphone, there’s an app for the CAT scales that will enable you to weigh your rig without even going inside. It’s called “Weigh My Truck”, and it’s simple enough to use (just don’t try to download it and set it up the first time while you’re at a truck scale with impatient tractor trailers behind you… true story). Using the app can be a convenient way to go. 

CAT scales are typically certified monthly to an accuracy of about 20 pounds, so you know the figure you receive is valid. So, if your weight figures are considerably different than the manufacturer’s figures and a salesperson or tech tries to tell you the scale you used must be wrong, it’s not. Look elsewhere for your new RV. 

But if you don’t have access to the app or you just don’t like using them, you weigh your rig old school. First, if you’re unsure about anything, you park away from the scale, go inside the truck stop to speak to the person operating the scale. Once you’ve got your bearings, head outside and drive your rig into place in line at the scale. 

When it’s your turn, drive on to the scale. There are typically multiple platforms on the scale, and you’ll want to make sure to position the axles of your rig on them appropriately. See the sidebar for details. 

On the scale, hit the intercom button and tell the weighmaster you’re ready if the intercom use is the local procedure. Some scales use a red/green traffic light that lets you know they have the figures and you can clear the scales. They’ll ask you for your truck number—you won’t have one, but you can just say something like “private vehicle,” and they may not ask if they can easily see your rig from the office window. This is part of the procedure the weighmaster will explain the first time you go in and ask.  Keep everyone inside the vehicle and wait for the weighmaster to tell you you’re finished.  

Once you’ve been given the go-ahead, drive off the scale and head inside, and get your weight slip. It will show the total weight and the weight of each axle.  

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Once you know your rig’s weights, you can compare them to the limits on your weight stickers and also use that information to determine your correct tire pressures from tire inflation tables. The peace of mind from knowing your RV is operating safely is well worth the time invested in getting it weighed.