Introduction to RV Weight Ratings & Why UVW is Important

Introduction to RV Weight Ratings & Why UVW is Important
Learn what numbers to check to keep your RV at a safe weight.

Knowing your RV's weight ratings is important for safety, stability, and to determine how much gear you can bring with you on your adventures! 

In the video below, James from The Fit RV sits down with Winnebago’s Senior Manager of Engineering to go over the basics of RV weights and share more about why UVW is another important number to keep in mind and why you may not have heard of it before.

If you have follow-up questions, join the conversation on this page of The Fit RV website.

Important RV Weight Terms

If you are new to RVing and trying to understand the basics of RV weight ratings, the following terms will give you an overview of what to pay attention to.

For more insights on why it is important to have your RV weighed, read this article.

Gross Vehicle Weight Rating (GVWR): Your RV and everything inside or on it

GVWR is the maximum allowable weight of the fully loaded vehicle (including passengers, modifications, fuel, fluid, and cargo). The Gross Vehicle Weight can be measured at a CAT Scale or other RV weighing service, and that number should not be over your GVWR. 

If you are over GVWR, you are no longer in compliance with the safety systems on that unit, including your brakes. Note that the weight on your hitch does also count toward your Gross Vehicle Weight. 

Gross Combination Weight Rating (GCWR): The vehicle plus what you are towing

GCWR is the maximum allowable weight of the towing vehicle and the loaded trailer (including all cargo, fluids, fuel, and passengers) that the vehicle can handle. This is usually higher than the GVWR.

In order to safely tow a vehicle or trailer, you should also look at your maximum towing load and maximum allowable hitch load for your vehicle. Be sure to keep in mind that how far back your hitch carrier goes out will change how much your hitch can safely hold without causing damage and safety issues. 

Important Note: The towing vehicle's brake system is rated for operation at the GVWR, not the GCWR. Separate functional brake systems should be used for safe control of towed vehicles for trailers weighing more than 1,500 pounds when loaded.

Gross Axle Weight Rating (GAWR): Ensures weight is spread ideally between axles

GAWR is the maximum weight that each axle is designed to support. The front axle rating is the Front GAWR and the rear is the Rear GAWR. The Front and Rear GAWR are listed on a label inside the driver side door jamb. 

Making sure there is not a corner of your RV that is heavier than others is also important to not overload the weight rating of your tire on that side. If putting on new tires, be sure to check that the weight rating will be high enough for your fully loaded rig.

When loading cargo or passengers onto a vehicle, it's important to distribute the weight evenly between the axles and ensure that the total weight does not exceed the GAWR for any individual axle. This helps ensure safe handling and performance of the vehicle.

Unloaded Vehicle Weight (UVW): Helps determine your Cargo Carrying Capacity

UVW is the weight of a vehicle as manufactured at the factory. It includes full engine and generator and LP fuel tanks and fluids, if applicable. It does not include cargo, propane, or occupants. 

Chassis manufacturers designate a maximum UVW that RV manufacturers have to abide by when upfitting a motorhome in order to maintain EPA certification for emissions for the vehicle as well as the Federal Motor Vehicle Safety Standard #301. FMVSS 301 is a U.S. federal regulation that governs your fuel system integrity. The primary purpose is to reduce deaths and injuries resulting from post-crash fires caused by fuel spillage or leakage during and after motor vehicle collisions.

UVW is subtracted from the GVWR to obtain Occupant and Cargo Carrying Capacity (OCCC). This is the number RVers often care most about since it determines how much gear you can bring along with you. Winnebago makes sure to focus on UVW to maximize the OCCC for owners and, more importantly, to maintain safety.

Note: If you can’t find a UVW number, find the “Max Dry Weight” or “Max Curb Weight” information for your chassis, subtract that number from the GVWR to obtain a sort of “minimum OCCC” for that chassis. If you do these calculations on an RV you’re thinking of purchasing, and you find that the OCCC is less than it should be … you might want to ask some further questions to see how they arrived at those numbers.

We hope this article helped to clarify some questions you may have about RV weights. For more educational resources for RVers, browse these articles.