Friday, September 22, 2023


Know Your RV: Know your measurements

Really knowing your RV covers a lot of ground. But before your first trip out of the driveway with a “new to you” RV, there are some important things to know about your RV. You need to know your RV’s measurements. Shoe size? Suit size? Ah, it’s a bit different!

Height first

A super-critical one of those measurements is your rig’s height. Push through a low underpass or try and fit under a gas station island roof could prove an undoing. You need to know precisely how “tall” your rig is above the roadway.

How do you measure your RV height? It’s easy to just run a tape measure up to the roof line and down to the pavement. But remember, there’s other stuff that sticks up above the roof line. Perhaps the tallest is the roof-mounted air conditioner. Since a tall object may be in the middle of the roof, getting the height figured out can be a bit challenging.

Measuring height means accessing the roof. A well-placed ladder with a spotter to help can get you up there. If you have a roof ladder mounted to the rig, you may be able to get up using it. Be careful. Test it carefully to be sure it’s firmly mounted and the hardware is good and tight. Once on the roof, it’s best NOT to walk on it. We work our way around on our hands and knees. Or you might put down “walking boards” to better distribute your weight.

Once you’ve found the tallest part of your rig, you’ll need to measure its height above the roof line. Then simply add that measurement to a measure from the roof line to the pavement. It can be more challenging on a fifth wheel, where the roof may not be the same height from front-to-rear. You may need to find something to act as a straight edge. We’ve found something like an aluminum or steel flat bar from the hardware store works good. It’ll need to be long enough to reach from the object on the roof, out to beyond the roof edge. With a helper measuring from the ground up to the straightedge, you’ll have your answer.

Length and width

measurementsWith height out of the way, you’ll also need to know length. This, again, is a measurement you make, not a figure provided by the RV manufacturer. We say this because those numbers may not take into account added stuff. A bike rack. A platform shoved into the hitch receiver. Measure the distance between the farthest objects between front and rear. And don’t forget to hitch up your “toad,” if you’ll be using one, and include it in “hitched up” measurements.

You may also find a need to know your width. Measure from the farthest side-sticking objects, typically your rear view mirror set.

Hit the scales for weight

Finally, another important measurement is your rig’s weight. There may be occasions when you’ll need to know if your rig is light enough for a roadway or bridge. Knowing your rig’s weight can be a complex issue, particularly when we talk about knowing weight for tire safety. It’s a bit more complicated than we can talk about today, so for our purposes now, knowing the rig’s weight on all its tires will suffice.


It’s best to have the rig loaded with gear, fresh water full, and with a full fuel tank. A quick, easy, and relatively inexpensive weight check is at a local truck stop. Many have commercial scales. A popular “brand” is a CAT scale. You’ll need to check with the clerk at the fuel desk. They’ll give you instructions on how to pull onto the scale, and when to move forward (or back) so you’ll not only know your rig’s complete “gross weight” but they can also provide axle weight information. Don’t forget to add the weight of passengers in your figures. Follow this link to learn more about using CAT scales.

Where to carry all that information

measurementsArmed with all these important measurements, what do you do with them? Height is perhaps the most common “accident causer” if not known and applied to driving situations. We recommend this: Write down, or print out, your rig’s height in feet/inches and meters/centimeters. Post that information in a conspicuous spot where the driver can easily see it. The other information should also be kept in “the cab” so it can be referenced quickly when needed.

Tune in next week for more “Know Your RV” tips. And if there’s something about your RV that you’d like to know, drop us a line. Use the form below, and insert “Know Your RV” on the subject line.

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Other stories by Russ and Tiña De Maris


Russ and Tiña De Maris
Russ and Tiña De Maris
Russ and Tiña went from childhood tent camping to RVing in the 1980s when the ground got too hard. They've been tutored in the ways of RVing (and RV repair) by a series of rigs, from truck campers, to a fifth-wheel, and several travel trailers. In addition to writing scores of articles on RVing topics, they've also taught college classes for folks new to RVing. They authored the book, RV Boondocking Basics.


  1. Height, length, and 4-corner weigh is one of the first things we did to the RV.
    Used the 2×4 laid across each roof A/C, and measured the height. We then added 2 inches to the maximum. Anything marked 11′-6″ we pull over, I climb the rear ladder and my wife inches forward. If it’s too close, we back it out.

  2. As far as measuring height with the straight edge technique, I would suggest that the person on the roof, holding the straight edge, use a level to ensure the strait edge is level at the time the ground person is reading the tape. Plus think of the possible ways error can be induced using this method and account for them. For instance are you measuring from the top or bottom of the straight edge? Should the length of the tape measure itself be accounted for?

  3. I added 6 inches to height, 500 pounds to the weight of my Cat verified weight, and 3 inches to the width of my motorhome measurements . Especially the height, you never know if they added road surface and did not change the signs. I also use a truckers GPS and can input all of these into it. Having these posted where I can see them easily saved me once in a construction zone!

  4. For Class C and Class A RV’s, “TAIL SWING” is an often overlooked critical number to know and understand,


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