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How bad is it if I tow more than my truck's towing capacity?

Before you drive off with a boat in tow, you need to make sure its weight is within your truck's towing capacity.
Before you drive off with a boat in tow, you need to make sure its weight is within your truck's towing capacity.
©iStockphoto/Tim McCaig

It's been a long week, and you're ready to hit the road on a much needed fishing trip with the guys. Luckily, your pickup is full of gas, your gear is secure in the back and rush hour traffic is starting to die down. Then your friend arrives and starts to hook his 20-foot (6-meter) boat onto the hitch. You start to tell him it's probably not a good idea for your truck to haul quite so much weight but think better of it. Those towing capacities are understated anyway, right? Besides, you're not going terribly far, and you've used your truck to tow before.

Bad move.

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A car's gross vehicle weight rating (GVWR), also referred to as the truck towing capacity or vehicle towing capacity, is serious business. A towing capacity rating is based on the maximum gross vehicle weight (GVW) (the weight of the fully loaded vehicle or trailer, including cargo and passengers) the vehicle is designed to carry. Exceeding it can not only damage your vehicle, but it also puts your life and the lives of others in jeopardy.

Understanding (and heeding) your truck's towing capacity -- specifically its GVWR and GVW, which are sometimes referred to as gross trailer weight rating (GTWR) and gross trailer weight (GTW) -- is one of the most important things you need to do before heading to the great outdoors.

Towing is no small feat and often requires a special beast to get the job done properly. Among other things, tow vehicles need stronger frames, suspension systems, engines and axles to handle larger loads. Just like you wouldn't dare cross a bridge made out of Legos for fear it would collapse under your weight, you shouldn't force your 1992 Ford Ranger to carry a boat that eclipses your truck's towing capacity rating.

If you're simply not satisfied with the simple version of "do not exceed the GVWR under any circumstances," turn the page to learn what could await the rebel in you.

That last bag might have been a bit much.
That last bag might have been a bit much.
©iStockphoto/Harald Tjostheim

Just because your pickup might be able to manage the extra weight of the boat for a quick trip doesn't mean it's OK to do. Your ailing grandmother could probably carry a heavy backpack across the room too, but would you really ask her to do it?

Just like repeated trips across the room with a bulging bag would put a strain on Nana's back and likely lead to broken bones, a few trips to the mountains with that four-wheeler will put a similar break in the life of your truck. Vehicles are designed to handle only a certain amount of force, and the way they're constructed reflects that. That's why commercial trucks that regularly haul tons of cargo across the country have significantly bigger wheels, more powerful engines and stronger braking and suspension systems than do passenger cars.

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When you ask your truck to pull more than it was meant to -- exceeding its towing capacity -- a number of things start to happen: The brakes begin to fade, the added weight contributes to tire failure, and the extra work required of your engine causes it to overheat, which, in turn, overloads the drivetrain and shortens the life of your transmission.

Although you may not see the effects of exceeding towing capacity at first, the gradual wear and tear will lead to eventual failure. The best case scenario is repeated trips to the repair shop; the worst is a major wreck.

Of course, if you insist on pulling an overweight load, you may not even live to see the effects of this wear and tear. That's because the extra weight pulling on the back of your vehicle significantly hampers your braking ability and steering control. When the back of your truck is loaded down, the front tires come up, causing them to lose some traction with the road. Without those front tires firmly on the ground, you'll definitely see a negative impact on your stability and handling. Your truck's brakes, which were designed to stop a limited amount of weight, will either take much longer to slow the vehicle down in an emergency or they simply won't work at all.

So do yourself a favor and forego the fishing this weekend. Your truck and your well-being will thank you for it. For tons more information on towing, hitch onto the next page's links.

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Related HowStuffWorks Articles

More Great Links

Sources

  • Cook, Miles. "Trailer Towing Q&A." Edmunds.com. (Oct. 13, 2008) http://www.edmunds.com/ownership/howto/articles/44921/page001.html
  • Kerekes, Charlie. "Changin' Gears." (Oct. 13, 2008) http://changingears.com/index.shtml
  • Smith, Bruce W. "Trailer Towing Illegally." Gulf Coast News. (Oct. 13, 2008) http://www.gulfcoastnews.com/GCNautomedia071408.htm
  • "Trailer Loading and Towing Guide." Sherline Products Inc. (Oct. 13, 2008) http://www.sherline.com/lmbook.htm
  • Webster, Rick. "Trailer Towing Tech." 4x4 Review.com. (Oct. 13, 2008) http://www.4x4review.com/feature/trailering.asp

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