Understanding Gross Vehicle Weight Ratings

When shopping for a used boat, assuming you already have a tow vehicle, it’s important to know how much the boat you’re interested in weighs on its trailer, and what your truck is capable of pulling. If you buy more boat than your truck can haul, you’ll have to shop for a new tow vehicle, too. True, there are worse problems to have, but it can get expensive if you’re not careful.

Factory hitches usually have the class and tongue weight capacity written right on them.
Factory hitches usually have the class and tongue weight capacity written right on them.

Typically the gross trailer weight rating (GTWR)  is indicated on a plate on the trailer tongue. If it’s not there, you just need to know the boat’s weight, its cargo and passenger capacity, and the trailer weight. You also need to know the tongue weight. If those are less than the towing capacity of your truck and its hitch rating, you’re good to go.

It’s a good idea to have a buffer between your GTWR  and the vehicle’s towing capacity. I like to leave 1,500 pounds in excess. That way, you’re not asking everything of your truck each time you tow.

Your gross vehicle weight rating (GVWR) is listed on a sticker on the driver’s door. GVWR is the maximum weight allowable for the vehicle, and it includes the weight of the vehicle, plus the weight options, accessories, cargo, and passengers.  It also includes the tongue weight of the trailer you are towing, so to help ensure that you do not exceed your cargo or payload capacity, you must include the tongue weight in the GVWR.

Knowing and understanding the  GVWR  of your tow vehicle is important in safe towing because it tells you explicitly the maximum amount of passengers and cargo you can safely carry in your truck or SUV. GVWR is constant and does not change, regardless of what you tow. It’s engineered in when the vehicle is manufactured. And because you know that tongue weight must be included in the GVWR, you know how much weight capacity you need to have “left over” for when you hook up your trailer.

For example, if you have a 5,000-pound truck with a 6,200 pound GVWR, you can safely carry 1,200 pounds in the vehicle. If you are towing a trailer with a 300-pound tongue weight, the amount of passengers and gear you can carry decreases to 900 pounds.

Again, it’s usually a good idea to get a vehicle with a bit more capacity than what your currents needs are. But at the very least, be certain the towed load and tongue weight are within your vehicle’s capacity.

Another example: Let’s say you have a 5,000 pound boat and trailer. With a 6,700-pound towing capacity, a two-wheel-drive Toyota Tundra with the five-speed automatic transmission and 4.7-liter V-8 would be a good choice. Its capacity is a little bit more than what you need, and that’s just what you want. Tongue weight should be 7%  to at most 10% of overall trailer weight, which means a Class III hitch would be best. A Class III hitch is rated from 350 to 600 pounds of tongue weight, which, again, is a little more than what you need, and that’s just what you want.


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